First semester is pretty heavy in terms of number of classes you take and most days run from 9am to around 4pm (on days you don't have lab, you'll be done early). Second semester is a bit lighter in terms of the amount of time you spend in class, mostly because labs are shorter and once a week. On weekdays I pretty much attend class in the mornings, take the afternoons to eat dinner, work-out, run errands, etc., and spend the rest of the night studying. Weekends depend on how busy it is with school. If it's a weekend following an exam week, I will take a day off and go have fun (it's also when I schedule family visits or fly home for the weekend), but the more the semester progresses and approaches finals my weekends consist of studying most of the day (although on weekends I usually try to get out of the house and do my work at a coffee shop).
Miami is an awesome city and can definitely be a distraction, but only if you let it. I don't think that it'll be an issue though because you will get so absorbed in school that you simply won't have time to go to the beach and golf whenever you feel like it and you'll be so busy that it won't cross your mind as often as you think it will. However, Miami has plenty of options available for when you do need a break or have free time (and you'll have that, don't worry).
There is a summer semester at Barry that begins in May and ends in late July, which is followed by summer break that runs until late August.