Help with Memory Stick folder names & what goes in them

[PSP>DS]

Alright, I don't really HAVE a PSP yet, but I know everything about the one I'm getting, and I'm also already readying my homebrew for it. However, I don't know where to put some stuff. Here are my questions:

Where do I put music, videos, and photos in the /PSP folder?

What music/video/photo file extentions are compatable with PSP in these folders? (ie. .mp3, .mov, .png respectively)

Can games/homebrew put in the /PSP/GAME150 folder be played as long as a CFW is installed?

About how large are PSP retail disc games and PSP movie discs (file size, not measurement size)?

Thanks in advance,
-PSP>DS

[kamenrider]

Format your memory stick using your psp and the folders names speak for themselves.

Its not about file extension, its about what file types the psp supports.

Yes you can only play backups and homebrew on psp's running custom firmware

UMD capacity is 1.8gb