ADEC housing (Abu Dhabi)

hello. Moving to Abu Dhabi in august to teach. Wondering how they go about getting my family and I housing. Do they tell you exactly what building you are assigned to live in, do they give you a few options, or do they give you a set amount for monthly rent and you pick the place? Just wondering how helpful they will be, or if I'll be doing a lot of the leg work.

Also, How long does it take to get residency visas for my family?