Setting up the essentials
Alternate PSP software to run PSX roms. Selecting the most compatible PSX bios to run your backups by holding the R button dowhen rebooting.

Backing up your UMD's in 2 steps
Use select menu to change the data output in USB mode to UMD and then copy the iso to another computer. Requires a Windows PC. Renaming is ok.

Impaler's Multidisk popstation GUI
Can read and run from back up drive and write to back up drive. Do's and Don'ts with multiple eboots

Best EMUs for classics:
Snes9X TYL - SNES
gpSP - GBA
NesterJ - NES 

Dimensions for the PNG files for your icons and backgrounds on your psp
-icon0.png (icon, 144 x 80 px, 32-bit PNG file)
-pic1.png (background, 480 x 272 px, 32-bit PNG file