Brewology

1) You need a phat battery because you can't make a Pandora's battery on a Slim battery
2) You need another homebrew capable PSP to make the Pandora's battery because to make it you need to run homebrew programs from the PSP which you would need it homebrewed to be able to do.
3) Yes, one memory stick will be fine.

Reigo you can make a pandora with a slim battery(i did it ) but it onvoles opening it up and you cant use the battery as a normal one after that. Also you can make the mms with a total newbie installer

http://www.pspbrew.com/forum/viewtopic.php?t=11076

that link will show you how to do it with only one psp but you are going to need another battery...or just play off your power cord.

or you could buy a datel tool battery its a premodded battery