You've got things slightly confused there..
You've got Commodore 64 which will be disk images.
the PP as already mentioned are Preservation Project files, you might need this as I don't know how extensive the nointro C64 dats are.
C64 Tapes are tape images, not all C64 games came out on disk, not all of them came out on tapes, but some will have come out on both
Amiga, Plus4 and VIC20 are completely different machines entirely and are not related to the C64 but if you want them go ahead and get them.
One thing to bear in mind is that with nointro sets, as far as I'm aware it means they are all uncracked..so if a game requires manual copy protection and you don't have the manual..you won't be able to play it..
For C64 games you're better off with the GB64 collection.