Hi there, I'm Fernando (24, Spain) and will be starting in Lux next August too.
I haven't tried searching for apartments with the list they send you, although a spanish guy who is working at Maastricht told me he had no problem doing the reservation...
There are some real estate agencies in the internet in Kirchberg and Luxemburg that will also find you a place to stay, some of them might also have pics of the apartments. If you send me an email I'll send you a small list with the agencies I found.
See you all later,
Fernando