The most important thing to look at is the historical operation of the property, then factor in the expense ratios or nearby properties, consider the differed maintenance, age of building, class of building and other operational expenses you may add or subtract to optimize NOI

I'm keeping my rental properties and will continue to seek out more opportunities. 

Industry average has operating expenses at 30%-35%.

I include the following: personal financial statement, 1,3,5,20 year business plan, prior two year tax returns, and my companies operating agreement.So, if you made $50k per year, divide that by twelve and you get $4,167.00, then multiply that by .45, and you get $1,875.00. 

For example, I find a duplex for 200k that needs 20k of work to get rented and operating.

Any recommendations for real estate agents that operate in those areas?

Should I first secure a pre approval for what I am qualified for or should I just continue looking at properties.

The big picture is this: Airbnb/VRBO/short-term rentals can continue mostly unabated.

I will let the tenants pay the debt, write off the interest, and continue to grow a larger portfolio!

You will need to confirm with local building dept if you will need continuous insulation. 1) remove siding and install sheathing with insulation adhered to it.