To answer the OP directly:

1) - unfortunately, not really. There are still people playing, but it's either kids fooling around in combat mode or the hardest of the hardcore racers on HD Phantom. It will be difficult to find a good entry-level race, especially in wipEout 2048 (I still don't understand why everyone plays the - in my opinion less suited to multiplayer - wipEout HD/fury)

2) - if you like things sitting on your shelf, or if you enjoy having to put things into things to switch games, then yes. Otherwise please get the digital copy, it's cheaper AND you get an extra ship.

3) - YES it will run buttery smooth on 1080p. NO, no disadvantage at all against PS4PRO - UNLESS you have a 4K TV or want to try the absolutely, mindblowingly amazing PSVR mode, in which case YES, a PS4SLIM will give out a lower res image. No difference in framerate though.

Hope that helps and see you online maybe!