Add a second claim for adverse possession in case the court sees the original purchase price as inadequate.

The last thing you want to do is have the courts decide who has to pay out who if you guys split.

If they took a shortcut on something simple and obvious like wallpaper, they probably took a shortcut on something complex and costly buried in a wall somewhere.

I think that argument would carry in many court cases unless there is more to the story.I'd encourage you to have written requirements that you can make available to applicants. 

Some ideas I've had are to start selling off properties and try to 1031 exchange into an apartment complex with management or sell off properties and 1031 exchange them into properties closer to where we want to move to. 

I'm looking into potentially purchasing a 12 unit apartment complex and am trying to figure up my deductions.

If your main tax complexity will be through real estate, then you can connect with one of the firms here on the forums.

Once you are up and running if you decide to scale then maybe looking into your own direct to seller marketing could benefit but it also adds more complexity and time involved.

You can't take an authorized occupant to small claims court or collections, but they are also easier to swap out. 

If you served them today to be out the end of November and then they didn't move and you are in court in December, they will ask for more time anyway (which the court would be inclined to give them some) and it will be January of February anyway.