Congratulations on your acceptance! I will try to answer your questions the best I can and if you have any more please feel free to ask. As far as class schedule we have mandatory classes M-Th and the hours vary from day to day. Classes usually start around 9 or 10am sometimes earlier and classes some days end at 12pm while others we go till 5pm. As far as studying goes we all study a lot including on the weekends. With that being said I value my sleep very much and have always felt that I can think better with more sleep so I try not to sacrifice it for studying. However, I have several friends who like to stay up really late studying so that is just personal preference. It's all about figuring out how to study effectively. You don't have an abundance of free time but many of us still found time to have fun (obviously this was before social distancing). Many classmates went skiing on the weekends, traveled out of state, went out downtown, went to games, etc. It's definitely not something you should be doing every weekend but most people would do something fun after exams.
As far as my experience so far I would say it has been very positive. The professors are fantastic and they really work hard to set you up for success in this program and help you accomplish your goals. My advice would be to not try and tackle this program alone I think its important to find classmates that you can study with and reach out to professors and tutors when you need help.
Congratulations again on your acceptance you are one step closer to your goals!