and as a bonus question, has anyone tried VOIP over one of these connections? I have VOIP at home and should be able to make calls from a laptop just as if I was at home, I think...
Yes you can do VoIP over Wifi but it depends on the number of users at any given moment, you might or might not get a good connection or voice quality. I have a Onesuite VoIP service and I always make VoIP calls over Wifi (free) on malls or coffee shops using my notebook. Sometimes I get a very good connection especially if there's only a couple of people with their laptops and sometimes I get really bad connection if the place is full.