Do wander spawn hordes move a significant distance on the overland map or do they pack and unpack on their source tile only. E.g if I provoke a horde in the city but manage to run them out of my reality bubble, will they unpack to where they were last in my reality bubble or to their source tile like the pawn store. Also, if I am building a base will hordes occasionally wander towards me and attack or do I have to aggro them towards it.
In my experience wander spawns do move outside of your reality bubble, but they do so slowly. The main thing that moves them around is loud noises, so unless you are making a lot of noise your base shouldn’t get overran. Ive only had my base get attacked after firing off some bullets while killing a jabberwock near my base.
I actually want to get attacked, what’s the point of deforesting the area if my nailboard traps and pitfalls don’t get used. I have spawn rates set at 50, what’s an easy way to make a lot of noise?
Set a house on fire and let it crash down. Always seems to bring the party.
Looks like it was mostly covered already. For noise, you can fire guns, set off explosives, honk car horns, etc. You can also lure a horde by going near it and yelling with shift+C. Do that a few times and you can lead an entire city worth of zombies anywhere you want, though it takes a while.
–Of course, there is always the chance that they will wander to your home whether or not you are loud: I cooked up a nice pizza dinner, then went to bed. In the morning, almost the entire right side of the screen was filled with zombies. 
–Here’s a tip: If a zombie horde is after you, and you can realistically fight it, set off an alarm to send down an eyebot. Zombie’s are idiots, and there is a good chance the entire horde will follow said eyebot instead of you. If you want to risk the awesome points, throw a grenade behind you and walk away. 
–Sadly, while the quick retreat didn’t end up in my death, it was a long time before I was able to get any of my loot back. 
I’m cooping up in an evac shelter that’s a bit away from the city😬 Car alarms and burning buildings aren’t an option, but just knowing zombies can randomly show up is helpful. Can’t wait for my three layers of defenses to be put to use!