Our counterparty has an attorney, who I believe would draft up the promissory note and personal guarantee documentation.

She seems like she may be in it for the long run, though, so keep documenting everything you can. 

You'll want to understand what kind or notices and documents you need to get executed to either up their rent or turn the unit.Solid long term tenants are worth their weight in gold in my book so if theres a way to up the rent and keep them happy I's say thats the best route personally.

When you buy the property, you are also buying the lease that is in place and the rights/responsibilities that go along with it, so it is important to understand what that document says.

And are they legally allow to do so without any signed document from the seller or at least hire them to do title work?

Link to new law: https://leg.colorado.gov/sites/default/files/documents/2024A...

Therefore, don’t let your referral sources gather documents for you or issue loan quotes.When is it illegal for a mortgage broker to pay a referral fee?

A lot of accountants now say that it is perfectly fine as long as it is documented as an arms length business like transaction.  

Have you look at your mortgage documents to see if there is a due on sale clause if not?

I think there is an overall misconception.If you don't receive a tax document(1099) does not mean that there was no taxable income to you.