Yes, disenchanting a level 8 Healing Aura enchantment from a found or purchased item will add it to your list of available enchantments (if you do not already have it). However, since any level of Healing Aura requires a malachite gem (which are limited), I would try to avoid using too many before you get a level 10 formula. Then again, I hoarded malachite gems (only added a couple Healing Auras and stuck to level 9 for other enchantments, and reloaded at malachite veins and certain quests in FoV which could give gems as a reward) and ended up with 65 at the end of DKS. Next game I'll either have to be less stingy using them, or not bother reloading.
While you can find or purchase enchantment formula, I probably got the majority of my formula by disenchanting equipment. I kept a list handy when I was playing with the levels of enchantment (and alchemy) formula I had, to refer to when checking loot or at merchants.
I thought the value of equipment did drop when you removed enchantments?
Silver and gold (large and very large) are the charms in Divine Divinity, though the same advice applies (only use the best charms on equipment you may be using for awhile, and they can not be removed). I did not use any charms in DKS, but collected 5 lesser charms, 9 minor, 27 major, 56 blessed and 61 divine charms (7 of which were vitality, 3 spirit, 10 strength, 7 dexterity, 6 intelligence and 28 other).
