I also didn't have to deal with mandatory attendance, but I can comment on the schedule the first two years.
MS1 year is mostly 8-noon lecture, with a few hours of class during the afternoons 1-2 days per week. It's very light compared to most schools, and you have a ton of free time. In the beginning of the year you have an exam nearly every Monday, but they cover a limited amount of material. Exams start spreading out toward the end of the year, but they cover more.
MS2 year there is a lot of lecture. Probably 8 to 4 or 5 most days, with 1 day on average until noon. The biggest concern with this is that in the past many students stopped attending lecture during second year to focus on step 1 studying, which is no longer possible. You do finish sometime in March and have ~8 weeks to study for step 1, so there should be enough time on the back end to make up for it. If you are trying to crush step 1 this will be a tough, but manageable year.
I'll try to check this thread periodically and answer questions.
