I need some guidance/best practices of how much to pay the lender for the money and how to set up the promissory note. 

Fortunately, in the scheme of things, this isn't a big deal.I'm not famiilar with Maine practices, nor am I a lawyer, but what your tenant did would be normal for a tenant on a month-to-month lease who does not want to sign a new 12 month lease. 

I would definitely tell them that the second room is unusable as a “bedroom” because they have chosen to put the washer and dryer in there.I’d say something along the lines of, if you put the washer and dryer back (wherever it’s really supposed to go) and turn the room back into a practical bedroom then I will offer “X” amount of dollars.

Using this method you could essentially save and continue to build on that 20,000 or you could put it into the property to increase the value while simultaneously increasing the rent.

But even then, tenant practically paid my mortgage for me....

We want to acquire a few smaller properties to start/practice with and then grow from there.

I agree, sounds like the most practical way to get it done. thanks @Pratik P.

Disclaimer: While I’m an attorney licensed to practice in PA, I’m not your attorney.

But maybe worth checking.Disclaimer: While I’m an attorney licensed to practice in PA, I’m not your attorney.

I don't know why you're having a difficult time finding a bank to do a refinance for your investments.This is a very common and typical practice so I would suggest calling a few more banks or credit unions.