Dead mobs now turn into a corpse which is basically a static container. The content of the corpse depends on the creature type. For animals, it's generally raw materials : meat, fur, hide, scales, ... You won't find gold pieces or a sword on a worlf corpse. Humanoid and intelligent creatures will 'drop' more interresting things (armor parts, weapons, ... random parts of what they are wearing when you kill them).
I drop some gold pieces at random places in the dungeon (ok, gold pieces in a sewer is not very realistic but it's always rewarding to see a '$' character on the map!). The total amount of gold depends on the dungeon difficulty and the level (the deeper you are, the more gold you find). Gold pieces are just munchies. The real wealth is in chests guarded by some boss creature. Experience points will be awarded when you manage to loot a boss's chest, or in some other conditions (reach a new level, find a secret area, ...) not when you kill creatures (this would prohibit any stealth or pacifist gameplay).
For now, you can only find food in a general store. You need to eat from time to time to keep your food level high enough. Every 10 seconds (real life), the food level decreases, and in the same time, your health points increase. As long as your food level is positive, you see a '>' on your health bar. Thus, the simplest way to restore health points between fights is to wait. If the food level reaches 0, you begin to be hungry and your health points stop increasing. If the food level keeps decreasing, you'll start to be weak, then feel faint and your health point will start to decrease until you die of starvation.