its a big part of the game that NPCs are drawn when you chop or mine, the further in the game the worse it gets.

for the raids you can just dig a mote around your base and nothing will get in besides flying enemies that come later on. just make sure its far away from the walls or else log trolls will be destroying anything within reach. then you just build and destroy a bridge into the base when you need to bring tamed animals in your base or anything like that.

"Can they be left outside any pens to "patrol" the village?"
you will want them on the outskirts because they howl like hell, and just build the standard work bench all over the base so every inch of ground is within the range of the bench so then nothing will spawn in your base. then you can just do a circle around your base and collect all the items they have farmed from anything that happened by. took me weeks of pain to get a level 2 wolf though and rolling back my save to the .old file because it got killed