Each program is going to carry their own guidelines for credit, income, employment history, debt-to-income and reserve requirements.

Can you carry losses forward as well?

The smoking deals I just had to cover the carrying costs.

well then if its zoned for that and utls are there then carry forward.. its pretty tough in our markets though with build cost to make sense of building a duplex.. vis a vi rent.but I don't know your rental rates.. building costs are 100 a foot  so probably 300k or so to build it to rental grade plus lot.. so maybe your all in for 400klets say rents are 1500 a side  that's not bad..

Both are hard and carry risk.

This is a BIG stick to carry around and ensure your tenants are behaving, especially if you are new to landlording.You can purchase the book here:https://get.biggerpockets.com/rentalbook/

If the tenants are on an 18 month lease, you run your analysis using current rents as projected income. this lowers your purchase offer, and punishes the irresponsible landlord for offering an 18 month lease at below market rents when he planned on selling. if the lowest price he is willing to accept is calculated using market rents, then you compare your risk aversion and capability to carry the property at a loss for 18 months to determine if it is worth buying still. likely not depending on how far under market rents are.

For VA's I am requiring an interview...I need to make sure they can carry my brand with each presentation.   

With turn-key specifically, I'm hesitant to enter higher cap rate markets, which by definition carry more risk.

Doesn't EVERYBODY there carry?