There are no cheat codes built into the game (at least not that were left in the release version). There is a trainer (somewhere) people have used to boost their stats and level, but I don't think it is possible to add items to your inventory.
Any apple will do for the sleeping person. Check merchants in the village (the bartender, etc), or there are a bunch of apples by the alchemist in the miller's cellar. If you head to the fjords (from the far south west of Broken Valley) I think I recall some apples being around the miner's camp there (the start of the fjords is safe enough, but there are level 18 opponents if you start down the mountain path).
