Your last question was in fact not answered, so:
PC ISOs: you dont need any emulator...they are PC CDs. Either burn them on CD or use a virtual drive, and use them the way you would use any other PC CD, like Morrowind or Diablo or whatever.
Amiga ISOs: Unless you have Amiga CD-32 ISOs, what you have are ROMs. The best Amiga emulator is WinUAE, which you can find at...err, just do a google search. Its a pain to setup, though. And you need a kickstart 3.1 ROM to make it work, and that is not especially easy to find. Personally, I gave up on Amiga emulation. Its just not convenient.
You will need a PSX BIOS for ePSXe. Do a google search for scph1001. The file you want is named scph1001.bin
You'll need plugings too; you can find those at zophar.net
The best ones are Pete's OGL GPU (OpenGL graphic processing unit) and Eternal SPU (sound processing unit). You dont need a CD-ROM plugin unless you play your PSX games from CDs - which you shouldnt do.
Configured properly, your games will look much nicer than on the real PSX (PSX = Playstation).
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