I would sort out the equipment and keep the best 2 or 3 of each type. You will find more equipment, but keeping some in storage will give you an idea how you need to distribute your stat points to use a particular class of equipment, and they will be handy as soon as you level up enough to use them.
Later in the game you will find belts, amulets and rings with slightly higher armour levels, though for the most part you'll be upgrading based on the bonuses.
I don't recall ever having to repair a belt. I had to repair weapons once in awhile, and the hero's main armour, but that was about it (maybe gloves a couple times). Unique and set equipment do not take damage (at least in the act they are found, and I think in general).
