1) dunno, i actually don't know if u do actually need up to more than 80gb of storage.
2) you don't need a HD television to hook up ps3. it will work just fine on tube tvs.
3) u can extend the amount up to 4 players. they use bluetooth.
4) you don't need to hook up to the internet to play games. but a lot of games CAN be played online against other players and/or friends. so they don't need to physically be in your house to play with you.
5) it's worth getting ps3 now. the version won't get any better. or you can wait another year or two for ps4 to come out.