@djbridjmurh
Congrats on getting in!
To answer your first question all freshman are in triples. But that’s a good thing! You’ll get to meet more people and having two roomates means that’s another person you’re hopefully friends with. The space issue is fine. There are two likely housing options. A classic and plaza. Classics are communal bathrooms no ac. Besides it being hot the first 2 and last two weeks of school no ac is fine. Plazas have private or shared bathroom and ac. Plazas are not very social in general and have a high amount of second year and maybe third year students. Classics are almost all freshman. My favorite dorm experience was in a classic. It’s the way to go if you want the best social experience.
For registering you don’t need to worry. There’s plenty of spots as long as you are flexible with times and professors. It’s random on assignment so not much you can do to change it.
It can be overwhelming going to a big school but once you come you’ll see everyone is very nice and welcoming. I can’t and most students cant walk on campus without seeing or running into at least 5 people they know. It’s a really tight nit community. Especially since 10,000 students live on the hill which is the UCLA RES halls in basically 2 square miles. My suggestion if you’re shy is do all the early orientation and zero week social activities. If it’s our of your comfort zone do it! College is the time to make the most of things and try new stuff. Also join clubs, IM sports or other orgs you are interested in.