tonsillolith: <Could somebody please explain to me why Karpov chose to move his a8 rook to d8 instead of playing his f8 rook to d8 and his a8 rook to c8. To me that seems more logical as Black does have the semi-open c-file, though I obviously lack the positional understanding Karpov had.>
I'll explain the best I understand. The two black pawns in the center are really important to have force behind. As Karpov shows, by advancing the d-pawn it is possible to clear the way for the e-pawn to pressure the center. When this occurs, black will not only have the pawn protected by the rook, but it will also be ready to push forward with the rook's strength behind it.
Another important reason for the black rook on e8 is an idea I picked up from Nimzovich's My System, which he calls the "mysterious rook move". Here black deters white from advancing the f-pawn in order to attack the black center, because by playing f4 and allowing black to capture exf4, white allows black to bring his rook into the game with more influence.
Considering that the c3 pawn is relatively well protected, I think the reasons I gave make a good case that a rook on e8 is more important than a rook on c8.
However, I really have a poor understanding of positional matters as these, and it's very likely I would have put my rooks on c8 and d8 too!