As a broad rule of thumb, the 50% Rule for SFRs states that about half of the rent will go to non-mortgage expenses.

Can you convert it back to an Airbnb for additional income and use the proposed rents to offset the mortgage so you can buy your new home? 

Keep in mind that when you are renting your place, these websites don't always talk to each other so check to see if your property shows up in a particular website. 

You might want to consider negotiating with the seller to resolve these issues as part of the deal.House Hacking: Living in one unit and renting out the others can be a great way to cover your mortgage and build equity.

If it's a rental, you can structure the loan so that the monthly PI is lower than the rent income.

Yardi tracks vacancy and asking rents at each property over 50 units on a monthly, quarterly and annual basis.

Do you mean completely turnkey and new or renovated and rent-ready?

Rent it and once your comfortable you can move one on the 2 property.

I am talking about current operating assets: what did they underwrite for rent, other income, RUBs, taxes, maintenance, turn over, etc.  

I don't know the detail as far as the tenant paying rent or not, if there's a lease contract etc.What questions should be asked before buying this investment opportunity?