1. 1GB stick atleast as most files tend to be 700MB
2. You need a USB cable to do the transfer. I bought mine for $10. http://hardware.gamespot.com/PSP-USB-Cable-Hip-Gear-15862-O-4-7 Depending on what electronics you have you could already have the type. I have two others that came with my MP3 players.
3. And of course the movie will have to be in a format the PSP can read so you may have to convert it.
ok i got a 1gb stick how many movies can i fit in there plus mp3s?
i got this usb that came with a file manager thingy
for the psp.trying to see if that will help ma convert the movie files