Can you fly these in the city? I must admit to never seeing any and I thought they phenomenon would have taken off by now. (Pun intended!) :0)
Permit and licence needed. You probably need claearance from ATC for take off too as the whole area is pretty much airspace Class D.
I'd need air traffic control clearance for just flying it about in a back yard or something?
Probably not for that. But flying over the city taking aerial shots will probably get you into trouble.