You should try using Ubiquti routers, switches and wireless APs. They are specifically designed for commercial type use with a lot users, and can manage traffic much better than consumer type devices. And they are priced reasonably. With Ubiquiti would not need to run an AP in each apartment, instead install one in the hall to cover three or four. Then manage traffic at the wireless router level. It can also manage different users and passwords.
www.ubiquiti.com