I approved for the tenants to start moving small things in on yesterday and I received a call from them that one of the current residents got very upset because they temporarily parked in their assigned space while unloading. 

What are good neighborhoods that I can buy pretty cheap in, and then either hold until I can make a good profit, or unload quick for a smaller gain.

I actually offered to move his stuff onto my trailer and unload it at his new apartment.. that was the only way we could get him out!

I have considered buying an Alaskan mill, and using my commercial lot as a place to produce my own dimensional lumber for making my own cabin kits.

I've been buying mine from lumber liquidators.

If the location is great, it will rent quickly in any market and will sell quickly if I need to unload it. 

Since they have no lease, do I still need to do certified letters, post public notices and sit on my hands while they unload everything in the unit some night, or can I at least cut their locks and install new ones? 

You are 100% correct that they are hard to unload when you are ready to unload them.  

He also said, you probably can make an offer because he has a few more houses that are not completed and he needs to unload one or two for cash.FAST FORWARD, A month later, which was yesterday my wife came home and gave me 2 vacant homes that she found on the way home and that house was one of them. 

For the flippers, I expect them to be trying to unload their fix and flips or convert them into rentals.