1) rooting is very simple
2) rooting allows you to put on an CUSTOM ROM much similar to a CFW sa PSP, the most popular custom rom right now is CYANOGENMOD 7 or CM7 pero maraming maraming cutom roms for multiple devices
3) if naka root ang you need to UNROOT bago i update then reroot
4) if naka Custom Rom and you want to get an updated ructom rom simply flash the newer custom rom on you device
5) pag nagkaerror sa rooting merong namang recovery, im not sure kung pano ireconv er pag error sa rom flashing/brick