They've been renting for $900/mo each, but I want to see the financials and proof of income. 

Next I’m going to read how to invest with no (and low) money down and Scott Trench’s recession proof real estate investing.

The nerves go away once you complete your first investment and you have proof in your mind that you can do it. 

Get written PROOF that they are out .  

To get the owner occupied rate if the previous owner was a non owner occupant you actually need to submit an application along with multiple forms of proof of residency.

My own financial situation is stable but commissions based, and I have 2 years of Airbnb income proof that come out to about $15k per room per year.

@Kevin Cespedes - Yes as Charlie mentioned, once you choose a lender to refi with (or a HELOC if that route is better for you), as you go through the standard procedure; proof of income, credit pull, etc... the lender will schedule the appraisal to ensure the property's value.  

You just make your cash offer, then when they ask for proof of funds, you get a proof of funds letter from a transactional funding co.

Do I print out and save an annual statement so if I get audited that is the proof required?

As the lender usually asks for 60 days of bank statements to make sure the funds are mine, how can I show the money I received in the proof of funds.Has anyone been in a similar situation before?