Use brew on the Idol of Bongu (with fire all around) - can be a little tricky finding the right spot where you can use the item on the idol and not get burned but you will get an increase - sometimes to a stat or gain a trait - these are permanent. You may want to SAVE your game before trying.
The prison cells are marked "H" on the map here:
http://www.ironworksforum.com/ubb/no...c;f=4;t=008143
they are furthest off to the "west" on the map. You'll find Grunaxe there.
Hope that answers your questions!
Wyv