Regarding raising the rent, you just tell him rent is going up and give him whatever notice you’re legally required to give. 

You are presently adrift at sea on your own and should be giving notice immediately to move out.

Fast forward, yesterday with A LOT of notice our hired realtor showed up at the house to get a key from my tenant for showings.  

Study the landlord tenant laws in the community you are buying and see how much notice you have to give your tenants before nonrenewal or look at cash for keys.

I have stopped answering phone calls and resorted only to written communication (for my records) but have noticed a pattern of very emotional and aggressive behavior from this tenant (as well as extremely unreasonable expectations about what the timeline is to have something fixed).

The only other problem is I notice uneven flooring, meaning in certain bedrooms there is a gap between floor and the molding. 

We never know when a bubble will burst, but after looking over trends in general, one can take grave notice to a few things changing rapidly in regards to real estate.

Rent IncreasesHow to Give a Notice to Vacate

As I am looking through the list of properties my agent has provided me, I have noticed that there are a lot of properties on the MLS with "unit rent" prices provided. 

Immediately serve a 5 day notice on the 5th day of late rent.