Two more mod questions; Nerfing backstories and changing stone type probability

[modtrying]

Two more questions I've run into. Is it possible to change the bonuses that backstories give to pawns? The current backstories give way too bog a bonus for me. I want to make it so most bonuses are +1 and +3 would be unusual.

Also, back to the world map generation thing, is it possible to change the probability of a stone type appearing in a spot on the world map. I seem to run into a lot of sandstone and would really like to decrease the amount of it generated on the world map.