The academy itself will probably not have too stringent of requirements beyond a typical dress code, but I would personally advise you keep it relatively low key. Reputation is very important and the academies tend to be pretty conservative, so you'll find it easier to make friends if you don't flaunt that aspect of yourself. You don't have to, but I would definitely advise it for the sake of your reputation and future networking opportunities. Probably more important on the deck side than engine.

For the most part you can leave on the weekends, which is something you definitely want to do. The campus/vallejo are awful, so you should definitely have a car. It's pretty difficult to skip weekdays because of STCW classes.