Sorry for thread necromancy, but I can provide a little info having worked for CEX for around 4 years.
My hiring, was simply handing a CV in (asked by manager in store to attend interview next day) and I got hired. Found out within 1 day.
From my experience working in stores though, every store does it a little differently.
Our store had a sign up in the window, when you applied, 9/10 we'd ask you if it was full or part time, CV's, we'd usually build for a week or two, up to 3 weeks. Then we'd look through them, discard the bad ones, and if you were selected for an interview, we'd phone ya. If you hear nothing back in a month, you probably won't get it, if they're just holding onto your CV, you may get lucky a few months down the line, it depends on if the store really has a high staff turnover.
Onto the interview. No email questions or anything like that, simply turn up for the interview (smart casual is better than full-on casual) and Suit is better than both of those. Our store would give you a sheet of paper, and give you 10 minutes to go round the store to write 10 things you liked, and ten things you didn't like. This gives you a chance to air some suggestions, and we found it'd help identify weaker staff to come.
As for the interview, again, depends entirely on the manager of the store. Most are fairly relaxed, they look for hard working staff willing to learn with product knowledge. Mostly they'll care more about your taste in games/music/movies, to show you have knowledge. Expect usual interview questions basically..
EDIT : Also, if it's part time you apply for, most stores love someone they can call at a moments notice and have them cover shifts, that's one of the largest things our store hired for, before I left, we had manager + 2 supervisors + 2 FT staff, we had 7 part time staff. after I've left store now has 8/9 part timers. So, biggest tip is to be available often.
Finally...if all goes well, our store would phone the people the same day, or within 2 or 3 days tops, if you don't hear back, you didn't get it.
Quite a simple interview process. Really what you need is to be confident, like the same things as the staff ! and be competent.
Again, sorry for thread necromancy, but this may help some people :P