Most of the chests you find playing the normal game have low quality gear in them. In the Everfall you have a chance to get good gear and in the DA island you have the chance to get the best gear. Some chests have BBI level 3 items and they turn into the best items in the game when you identify them.
Most of the items you find that say "combinable" can be combined in your innkeeper storage menu to make other items. I've never really messed with this, you can use it to mix nuts when health potions to get stronger health potions and stuff like that. Most of the items you find can also be used as upgrade material.