Cursed just means the item can't be unequipped without a Remove Curse spell. There are several really good cursed items that have no other drawbacks whatsoever. There are a bunch of really nasty ones, though, which can have to hit penalties or HP drain. Others have both positive and negative qualities.
The items you get from passing through the Land of Dreams are all cursed, for instance. But some of those items are the best in the game, and you might never even WANT to unequip them.
For the special powers, each string of characters is associated with a particular power. The original idea was that you'd write down which items had which strings, and after using them you could identify what they'd done. If you then found another item elsewhere with that same string, you could refer to your sheet of paper and determine what it did. For instance, +1 vitality and -1 age is present on a bunch of different items. In the modern era, it's probably easier to just download the Cosmic Forge game editor and look there.