Search in char.cpp:
PointChange(POINT_LEVEL_STEP, 1, false, true);
And change three times (every level step) to:
PointChange(POINT_LEVEL_STEP, 2, false, true);
I think that's all. It's not tested.
You can increase the mobs damage increasing their stats (like STR) with st, dx, ht and iq columns, damage_min and damage_max and, if you wanna multiply the damage, just use the column named as dam_multiply.