Dutch fansite SimParool has also asked a few questions to Maxis on The Sims 2 Apartment Life.  InfiniteSims was kind enough to post a translation.

Now that sims can visit neighbors on the same lot, is it also possible visit neighbors on other lots?
» No.

Are the magical world lots about the same as the special hobby lots from Free time?
» Yes, they behave in a similar way and only witches can visit them. They must be unlocked.

Is it possible to have a ceiling at the top floor when there’s already a roof on the house?
» Yes. Ceilings are a great new addition to this pack. You now have ceilings and can change their appearance. They work similarly to the way floors work now.

Head on over to InfiniteSims to catch the rest of the translated questions.