Have you had the doctor arrested yet? I though I read awhile ago someone else used that trick to cure all three patients.
Telekinesis / Wizard's Sight might let you grab some of the stuff from Kistandalius' place, but the only way you can get into the back short of killing him is take advantage of the short one-time distraction from the minstrel.
Save the game, put skill points into 2 or 3 of the skills and try them out, then re-load and try the others.
