Hmmm, this thread seems to have died, but I wanna give it a try anyways...
1. The bizarre/arcane sounding terminology
Well, I suppose it must have sounded pretty cool in the 19th century, and I suppose we could change it. However, I don't really see any point in changing it. Also, I think its pretty awesome to go to elders quorum or to be a high priest. To each his own I suppose, but as far as explaining it to friends and such, I agree that changing up the wording might help a lot
2. The Book of Abraham
Now I know that this might sound like a cop-out, but to really know if this is true you just have to go back to the basics... I struggled with this and a bunch of other anti-mormon sentiment for a little while, but what I did was just re-established what I believe from what I know and have had a witness of. The stuff that I just believe or at the time wanted to believe, but couldn't come to terms with was easily faltered and weighed very heavily on me. However, I knew and know that the Book of Mormon is true, because I have received that witness. Also I now know that Prophet Monson is a true prophet, from a personal witness. So pretty much if I know those two things to be true, I then must know that everything else within it is also true. People will try to explain to death their theories, and their objections. However, who's to say that the Joseph Smith translation was not the original translation then changed and altered over time by the Egyptians... I am not claiming that is what it is, but as previously stated, I know the Book of Mormon is true and Thomas S. Monson is a true prophet of God, and so in all things pertaining to the church are as well true.
3. The absolute lack of any genetic (with regard to the heritage of American Indians), linguistic (with regard to the language of the American Indians), or archaeological (with regard to artifacts/animals that would be expected to exist were the Mormon texts historically accurate) evidence supporting the historical claims made by the Church.
If you trust genetic, linguistic, and archaeological information then you just have to throw out all of the Old Testament, New Testament, Book of Mormon, ect...
However to break it down:
Genetic: We are talking over a two thousand year period, and can we truly trust genetic capabilities. Also, and I apologize if I go outside of church doctrine, possibly outside persons traveled to the Americas after or not recorded in the Book of Mormon. Which would put into question any genetic material found. Now again, I am sorry if I have said anything outside the bounds of church teachings or that which could be misunderstood as such. However, we just do not know enough about the early Native American life or honestly about current genetic capabilities we have today to truly be for certain on any current scientific understanding/ knowledge.
Linguistic: God is known for confounding languages... That's all I got.
Archaeological: Well, this is a hard field for Archaeologists. Often we have a full and well documented of something having existed, but there is no archaeological evidence... For example: it is very well known that there were horses in Mongolia dating back many years, but their was no evidence of it until 1990 and even that was found in a tomb. Also there is just very recent evidence of Lions in Israel. It took lots of money and time and resources and after many many years archaeologists just now found evidence of Lions in Israel, which greatly put the Bible to question for some. So, as far as archaeological evidence, personally it's no big deal to me.
That whole Black Thing
Well, it is clear that there were African Americans that received the Preisthood early in the church.Then of course there was that revelation that put a pause on it. So as far as racism, I am not so sure that that is the case. However, I know without a doubt that there were probably quiet a few racist Mormons back in those times.
Now the heart of this question mostly puts to question revelation in and of its self and not racism. So often times and likely even the majority of the time it is the duty of the Prophet or person to inquire of the Lord, which in turn may result in revelation. In the case of blacks and the priesthood, obviously the Prophet after the civil rights movement, inquired of the Lord as I am sure the Prophet may have been under pressure from the outside world. This however, only prompts the Prophets asking of the Lord. It does not bring to question the divinity and truthfulness of the revelation. If you have a question on that then you just have to start from the basics as I explained previously and work your way up to it. I however, wouldn't be so dismayed by the fact that a Prophet asks something of the Lord due to social pressures, because if we have a look into the Bible, then we will find that the Prophet at the time is constantly asking of the Lord because the people keep pushing him and prodding him. So it is certainly not unique to Christianity, Judaism, or even Islamic beliefs.
So overall, don't be overthrown by the potential delay or bring about of revelation returning blacks to the priesthood, but I would be more inclined to know what potentially may have pushed Prophet Young to inquire of the Lord in the first place historically speaking, or maybe he didn't inquire and it was just instructed him. I don't know as far as that, but this is my best shot at such a hard and faith crippling subject.
5. All or Nothing, and the Culture of Shame and Dishonesty
Now this one is kind of tough to explain... I am twenty-two right now, and when I was Seventeen I began having "relations" (sorry, trying to be G-rated) with my girlfriend at the time. Sorry to gross you out, but this went on for about six months before we got caught. I kept taking the sacrament mostly because I didn't want my mom finding out, or anyone noticing that I was potentially involved in having "relations" with my girlfriend that they all knew. So of course, I truly did not want to stop what I was doing, I kept hiding it. Well, eventually we got careless and were found out. My mom dragged my butt to the Bishop and he talked to me and was blunt and told me that I HAD to stop. There was no beating around the bush, and in all honesty if a Bishop was not direct with the members of the church concerning matters of such spiritually damaging activities, the members would not take it serious and would excuse themselves or just not care because they felt that the Bishop wasn't overly concerned. Getting back to the story though, I told him I'd stop, and I was just straight up lying through my teeth. There was no way I was going to stop at that age and time and without the perspective I have now, and obviously I didn't. And before I started with the "relations" I too felt that I was in good standing and I could tell that people thought the same. Well, long story short I ended up moving to Alaska as soon as I turned 18, my girlfriend followed and now I have a beautiful three year old that I love and adore more than any and all things in the entire world. In addition, we divorced when I was 20, I ended up moving to Cali in order to follow my son, and because I had no job or housing had to live in my ex's parents’ home... I was without a doubt depressed... So here is all that perspective I mentioned I had. Trust me, the story gets worse, but I'll leave it at that.
So as far as all the harshness your friend received, it sounds like it was likely with good intentions from someone that actually thought that yelling and screaming would encourage him to change his mind. Unfortunately, some members and even local leaders feel that they can push the envelope and beat the sin out of someone (figuratively speaking)... Which is NOT what the church teaches and is NOT how a Bishop, auxiliary, or any member should act or take upon themselves. Then on top of that, making any one feel unwelcome or not allowing them to come to church is so far beyond the scope of reasoning that the "leader" has no excuse. Even in the case of excommunication the person should still be welcomed and even encouraged to come all the time.
Now this is not to excuse your friend, he was endowed and took upon him sacred covenants that he should and unfortunately didn't regard as sacred and worth keeping. So action such as sacramental probation, priesthood probation, and up to excommunication should have been taken until he became worthy again. On top of this he served a mission and should honestly just know better, but unfortunately just because a person serves a mission or receives a high calling does not mean that they have a testimony and faith to match, it just means that if that the Lord felt that that person could have benefited greatly from that position and if that person wholly magnified that calling that he would benefit and thus be strengthened enough to hopefully manage the temptations that he was going through.
Now as far as the members partaking of the sacrament when they were not worthy. Simply enough, they just shouldn't have partaken. You may very much have been right in noting their lack of worthiness, but then again maybe they repented and you were just unaware. However, from personal experience often times we justify, reason, and over analyze our situation to best suit our wants. This is clearly wrong, and to those that unworthily take the sacrament, don't feel that they will be without justice, because the very bittersweet truth is that no one is free without justice even unto judgment day, when the Lord himself will analyze our faults and unrepentant actions.
So, the take away from all of this is that anyone and everyone I am sure could pick out faults or errors as a life is long, but to truly know as I can tell that you truly would like to know based on the length of your questions and inclinations toward understanding parts of the church if even the more controversial parts you must act on Moroni's promise:
"And when ye shall receive these things (i.e. The Book of Mormon), I would exhort you that ye would ask God, the Eternal Father, in the name of Christ, if these things are not true; and if ye shall ask with a sincere heart, with real intent, having faith in Christ, he will manifest the truth of it unto you, by the power of the Holy Ghost"
Remember to ask with real intent and faith (if even you just hope to have faith to believe). Then you will receive that same witness that I received and so many before me, and it will be like a feeling that is faint to recognize and will course through your very being. Then you will know.
