Handbooks are good, statutes are better.1. I believe they should give me at least 30 days notice, even for a holdover since I did pay the rent. Am I correct?
You aren't a holdover tenant. You have an agreement with the landlord for continued tenancy on a month to month basis. His acceptance of rent is evidence of that.
https://www.revisor.mn.gov/statutes/?id=504B.141
A month to month tenancy requires written notice by either party for one month through the end of the rent period.
https://www.revisor.mn.gov/statutes/?id=504B.135
Which, at this point would be through August 31st.
Yes.2. Just to cover me, should I send a certified letter to them? Should with my intent to vacate date be August 31st or Sep 30th?
But it's not likely to get to him any time soon and might come back unclaimed so I suggest you hand deliver it to him with a witness. If you can't get it to him over the weekend make sure you get it to him Monday the latest. Quote the statute in the letter. Keep a copy.
Make sure you also pay the rent on Monday for August (regardless of what he said about waiving it) (also with a witness). Pay by check or money order, make a photo copy and if he tries to refuse it just drop it on his desk along with the notice.
Make sure your witness is willing to go to court and testify if necessary.
I'm sure they can do a lot of things to you, many of which would be extremely unpleasant, but anything other than complying with the statute would be illegal and give you grounds for a lawsuit.3. I'm 100% sure I can't move by that deadline, what will they do to me?
I don't know. What if he fakes a notice?4. Given how sleazy this guy is, what if he fakes a notice, in case we go to court?
You address whatever happens when it happens.

