My written tenant acceptance criteria clearly states "documented income", so unreported and under-reported stuff does not count. 

If you use someone that is willing to help but has no idea what is required, no experience in how to administer a 1031 Exchange and/or what documents and language must be used/included, you will have a very difficult time during an audit. 

I have bought many condos though so one thing I would say to do is check the document carefully to see what they say about rentals.  

Just make sure that you have an attorney draw up the contract and that it is recorded with the county immediately after closing so that your right to take full ownership is documented.

If you want to classify the origination fees as interest expense, you can, you just need to disclose that in your statement of accounting policy.If you'd like to read more, go to page "FAS91-7" of the document below and look at #20 part B.

I am no expert here but I believe there is something called a "due on sale" clause in your lenders documents.  

You need to have a 506c offering and proper securities documentation. 

Structure/document the steps by which you accomplish the former and outsource them.  

This document, signed by the seller, is to transfer all the benefits and responsibilities of the written lease to the new buyer.

The broker typically has a processor at their office who aides the broker in sending out the application packet for signature and collecting the borrower documents to submit to Investor B.