It wasn’t overly strict back in the day but they had a curfew that you had to be back by the Yeshiva by 12. They may have cracked down since then but there’s a dorm counselor who lives on premises in mercazare at least that’s what it used to be) and he keeps an eye on things and tries to get guys to go to sleep at a decent hour.
I think you should try to get in touch with the Yeshiva and speak to them about any other questions. Its a good place and I know people who really turned it around there. The guys who turn around in mercaz are from the most solid grounded bnei Torah around. They have a great reputation in the Mir.