3. There are some in stock in stores, some are owned by townspeople or academically-minded villagers. The elders tend to have a small library in their homes. All are difficult to steal, and most are glyphed or warded against theft. They can be read while accompanied by their owner, if the would-be reader is persuasive and seems trustworthy. Remember, you're foreign adventurers!

4. There is nothing indicating that they cure anything else; blight is a known condition in this world, but normally they have plenty of adventurers bringing back crystals. The basic cure (touching the stone to the affected creature) can be done by anyone. Producing a more efficient curative substance will take some alchemical skill or the ability to follow instructions from a craftsperson.