The best plugins for me are, Pete's OGL vers. 1.50 set to nice and tweaked from in game, Pete's CD rom plug in vers. 1.5 w/asynch read on and 2x speed limiting, 7502 bios, still expermienting w/SPUS.
No, no one can tell you exactally where you may find a PSX bios. But if you go to www.google.com and do a search for PSX Bios you should come up w/plenty of sites that have them. The reccomended ones to get are the 1001 and 7502. These seem to work best for most people. Hope this helps.