I tried to comment on your blog directly but it was weirding out.
I had trouble with this same thing. I had made friends with people who were under 21 and in the end, its just not worth the risk. Like you said, you dont want alcohol to ruin your chances for a career with the company. You will see your friend often whether youre roommates or not and it'll be good to put yourself out there. And also, with the DISboards and the Facebook group and the aim chatroom, you'll become friends with people before you get to florida and probably find great roommates. Also, the roommate notification is just to have a specific person be guaranteed to room with you. if you show up to check in early, its more than likely that you get to room with those you are in line with so you have until day of to pick a roommate.
And under 21 people are allowed in non-wellness apartments even if youre drinking as long as THEY are not drinking.
I think i hit all the main points. Good luck deciding but i would go with non wellness!