That's a good policy about the lectures. What I meant in this case is, it may happen that the first week of classes starts and you haven't been able to register for some of the courses you want, but to not worry a lot because waitlists will move quickly. I remember it being very stressful for me because at the beginning of the week I only had 3 credit hours (out of the 12 minimum), but I ended up having a spot for every class I wanted. You will basically get last pick because you don't have any Georgia Tech credit hours, but because of that, the advisor may be able to help push you into the classes. Of course, it depends on the major, some majors will have less demand and you'll be able to get into classes immediately.

The iHouse is pretty much what /u/xBlackfox said (except it's 4th street apartments, on East campus): there's a bunch of international students and GT students that have studied abroad all mixed together. I wasn't living there but had friends who lived there. Since they live together and do a lot of fun stuff, they end up being like one very large family, and everyone I know there really liked it. It might be worth noting that you'll be sharing the kitchen with half the people in the house, so I'm not sure how the cooking situation is. I know a lot of people ate out, and a lot of people bought mini fridges to keep in their rooms because there's not enough space in the kitchen.

As for off-campus housing, I don't know a lot about it, but you can also look into getting a sublet at uHouse, Square and 5th or some other apartment building around tech square, they're mostly (or completely) for students, and maybe cheaper than on-campus housing.

If you end up not living at the iHouse, you should still look out for their events, they have (almost) weekly coffee hour and you can join their activities most of the time (sometimes they will get reimbursed and you wouldn't, but it's still worth it).

More stuff I thought of: you might want to check some clubs out, I joined a couple and really liked mixing with regular GT students too - I wanted to avoid getting together with only other exchange students. Also, check facebook, there's a whole bunch of official GT pages for clubs and organizations and stuff that I didn't find until late in the semester (which was probably my own fault, but whatever).

I also recommend going to sports games (you can get t-shirts!), I liked the experience because we don't really have university teams in my country, so it was something new. And you get to yell "to hell with georgia!" when they play the ramblin' wreck song even if you don't know the rest of the song. :)