Also...AFAIK, you don't have to change classes ever...but it makes the game more interesting and gets you more spell groups, skills, and traits.
On the Dragon Ore...in addition to "stealing" the key from Freyedies, you can also steal back the Dragon Ore from him and then give it to him again. You can have him create umpteen sets of Dragon Armor for you this way; enough for all your characters, plus plenty to sell (they sell for about 12,500 GP in the Armory).
Dragon Armor, BTW, can be worn by any character, including Warlocks and Wizards!
Put it on them and watch their AC soar. Bless it with AC (Artifact of Stone) and watch it soar even more!
Freyedies can only work on one set of armor at a time. As you get one set, give him the next ore and he'll start working on it. All you have to do to get him to finish is leave the room, then return.
-Sazerac