1. All downloaded games from the PSN are associated with a given PSN ID. Your PSP GO (or PSP-3000) can be associated (activated) with 1 PSN ID. Thus, if the game is on your PSP and you've activated the PSN account on the PSP, all games should work. One side note, the current activation limit for PSPs is 5 meaning that you can have at most 5 PSPs activated on a single PSN account at the same time.
I'm assuming the NGP will have something similar.
2.I haven't used the Go too much (only in stores). It seemed fine to me.
3. Yeah 802.11b directly on the PSP is a tad slow. Downloading on your PS3 or PC and transferring is much easier and not really buggy. You just need MediaGo software on your PC and a USB cable to hook up to your PSP.
4. Depends on your genre preference. MGS: Peace Walker is a masterpiece IMO. Both the God of War games are great (but short). Crisis Core, Jeanne D'Arc, Persona 3...I can keep going.
I've always wanted a Go to replace my 2000 but I couldn't find any cheap enough. $100 for Go 10 games sounds good to me :)
