Ad 1.
Each turn you tax 200% means about +20 unrest. Here is the table
http://dom3.servegame.com/wiki/User:...fect_unrest.3F
Killing brigands by patrolers is random, but 20 patrolers (with patrol strength 1, but bakemonos are slightly worse patrollers) is minimum, they sometimes catch 1 sometimes 20 brigands. Each killing brigands is -1 unrest, I guess. 40 bakemonos is safe number for 200% tax.
Ad 2.
Dom 3 wiki
http://dom3.servegame.com/wiki/Main_Page