So legally speaking, if I remediate the mold / have it tested and it comes back normal, I do not have to disclose to the buyer?

I am not an attorney so I cannot speak to the legalities.

Even if I do speak with a landlord, I keep in mind that they might give a positive reference to insure that their "headache" tenant moves out.  

I don't want to speak to which strategy you should use for decreasing your costs, but I would recommend examining your tenant screening process if you are having to actually go through the whole eviction process that many times.  

I did this at the beginning , I took courses on how to communicate with people , and public speaking as well.

Whenever i call, they either don't want to speak , and most don't soubd like they are motivated.  

I've only looked in Minnesota so I can't speak to how Minneapolis compares to the rest of the country.  

Too long to answer here in a concise paragraph, but I think you are off to a good start if you speak with @Russ Scheiderwho I have done a lot of work with in this market with off market deals.  

I did speak with my agent and there was not much information she could find, no listing agent, just the date the bank took back possession. 

You can seller finance to another investor as a commercial loan, but you're speaking about consumer financing.As I said, read here on BP, there are a few, not many, who know seller financing as it is required to be done today so be careful about what you read on line.