I'll chime in with "Ubiquiti Unifi" too.
Now..."how many"...and "how far apart"...and all those other questions...impossible to answer from my couch. You'll have to look at many factors, walls, structures, how many wireless clients, what kind of interference, a whole bunch of factors.
I'd run a bunch of ethernet up across the ceiling and sprinkle some around. You can have a few of them "repeat"...but you want to avoid that as much as possible, only using that to fill in areas that you can't get ethernet to.