Consult a qualified real estate attorney before entering into a sales contract calling for owner finance, and never use forms of the internet to document such transactions.

I'd respond in writing, that you are happy to look over any documentation they have regarding their claim. 

Make sure you take pictures, lots of notes and document everything you possibly can.

You still need to underwrite the property using all the required documents rolling T12, annual rent rolls, comps.

Again, without seeing the documents and putting in the research time, it's not possible to offer anything more than general advice.If you're unsure about treatment you may want to think about onboarding a tax professional who can dedicate the time to dive into the details for you.Best of luck.

I would like something that allows me to create "projects" on a per property basis and has places to place all the pictures and scanned documents (picture of front, picture of back, picture of kitchen, MLS listing, etc...), can do some of baseline calculations (like the BP calculators - which are awesome!)

If there isn't cash they will lend on rate and term but only based on purchase price and money that was put into repair the property that is documented with receipts. 

Triple check legal documents before you sign them.

The specific details are not as important as the language used to document the terms.   

In order to get the best interest rate on my refi (this is a BRRRR deal), my loan company has now told me that I am required to get a document filled out by a 3rd party property manager.