Can you mesage your friends while they are in HOME? Can you pick several different HOMES? for instance, a sports home, a regular home, an action home, etc. Becuase you might just have friends who won't play anything you have but only a certain genre.
Based on all the video footage and interviews from Phil Harrison, yes you will be able to send messages within Home to people on your friends list (see the GDC 07 keynote video)
Also, it appears that you will be able to have a basic, a better, and best apartment. The basic apartment looks to be free and the better or best apartments will most likely cost $$$. You decide what theme you want these apartments to be like. You can make your smaller apartment a sports lounge, the better apartment an auction spot (when that feature becomes available), and the best apartment can be the party crib (in the GDC 07 keynote, Phil demonstrated this when he went to the basic apartment and start to the best apartment via the virtual PSP.)