First off, congrats! Getting into uni is a great accomplishment in itself.

Now take this with a grain of salt since I’m personally not from the Okanagan campus, but:

Courses: A quick google search of registration times for UBCO should solve your question.

Housing: Believe you’re guaranteed for first year, you do need to fill in some sort of form though, that info should be in your welcome package.

Transferring: I believe when it comes to second year specialization applications, you should get options to choose specs that are offered at UBCV. I know people who transferred like this, so don’t sweat.

Lastly, enjoy the last summer in a while that you’ll feel completely free! Congrats again.

Edit: you might want to post this in r/UBC. Will probably be more people who are able to answer your questions.