For example, if you play through the game on easy and unlock the infinite face paint and SAA, could you play through a second time on normal with those items enabled? --- Real ninjas don't drive cars Official Village Idiot of PotD
No, the items you unlock are only for that difficulty. This eliminated people beating it on easy and getting the stealth camo and infinity face paint and then turning around and playing it on extreme with the same items. Its like that for every metal gear game.