Check to see if the unit you're joining has a Facebook or webpage. My son's unit has a FB page -- complete with pictures taken unit's S5 (public affairs midshipman). It would give you a glimpse into that unit.
I believe most units have a freshman orientation -- run by the AMOI (Assistant Marine Officer Instructor). At my son's unit, it was a week before classes start and lasted 4 or 5 days. Dorms were opened early. It happened to be the same week as sorority rush, so there were a few hundred girls on campus.
As far as weekly unit life, each unit runs differently from what I've read. My son's unit wears peanut butters (service uniform) one day a week and unit polo with khakis. One day a week is "service specific" PT -- Marine Options, MECEPs, and special warfare Navy PT separately from the SWO mids. The other day is unit PT -- mostly company vs. company.
One main struggle all ROTC mids have is balance. The unit expects you to keep good grades. It also expects you to be involved in "extra" unit things. During his freshman/4c year, by son was on the endurance team, rifle/pistol, and drill teams -- although he only competed with the endurance team. Every freshman was required to be on the drill team until official competition. All freshman mids all had mandatory tutoring and study hours. My son has cut back to only the rifle/pistol team this year. Having said that, there are other opportunities to be "voluntold" for special activities.
It can be mentally taxing to see the "normal" college kids not have to worry about getting up at zero dark early to PT, then go to classes, do drill time, etc. You've heard the term "embrace the suck"...sometimes you'll just have to work through the mundane. Having said that, it does make one better at setting priorities, etc. Personally, I feel the "semi-regimented" routine is tougher than the fully regimented routine of the Academy. There are pluses of being integrated with students that aren't like you, however.
If you have any specific questions, let us know.