Yeah Its possible, I actually pulled this off last year at where I work. I followed the screen replacement guide at http://www.ifixit.com ; the hardest part will probably be getting the damn things open:p
dont quote me on this, but i believe some had a batch of faulty power boards that wouldnt charge the battery or run off AC power. I heard it was a $10 part and a little time to fix, but still might be a thorn in your side.
Though I could have the completely wrong model here, and that laptop...
Im pretty sure you can, you just need to enable internet connection sharing on the laptop and set up your wireless for Ad-hoc(computer to computer wireless). However i dunno if the PSP supports that. Someone else here will probably know.
^^ what he said, but with actual grammar :p
I Have a 9300 and upgraded to 2 gigs, well one stick ended up going bad and I ran on 1.25 gb, and there really was not much of a difference between the two, you might notice slightly faster times when you alt+tab out of games with dual channel.