As a seminary student in WA, my experience is roughly the same as previously mentioned. However, it should be mentioned that you shouldn't feel pressured to make every day a formal lecture period. Especially when it's so early in the morning, sitting and listening to a lecture Sunday-school style is almost unbearable - wonderful scripture principles or not.
That's not to say that it should be total chaos and a zoo. It shouldn't, in my humble opinion. Especially if you're teaching freshmen.... :]
I'm a senior this year, and our instructor this year does a wonderful job of making the lessons more like general discussions of principles, or telling funny anecdotes. Once a week he'll also set aside ten minutes or so for us all to talk with him and catch him up on what's going on in our lives. The tendency (at least where I live) is to make Sunday school a really stuffy and formal experience. That sort of dry atmosphere does not work AT ALL when its 6 am and you're exhausted from writing a paper until the wee hours the night before.
As far as a dress code, for students standard modesty applies. The instructors in our stake wear Sunday dress, but I don't know if that's nation-wide or just our region.
Next year will be the New Testament, if it's the same across the country.
Hope I helped!