To help (every so slightly) with spawning monsters...
After I clear a monster, I tap one other building, wait about 20 seconds, then force-close my game. Wait about 20 seconds and open it again. It feels like it "clears the memory" and I can spawn a new monster in fewer than 2 trees and all my farmhouses! It's a pain in the neck, but so is using all my energy to get no monsters. And yes, I agree; the fangbeasts are really annoying right now =/