For instance, I'd recommend understanding the average expense ratio for similar properties in the neighborhood.

Average profit margin is probably around 10-15% before taxes.

This takes a little more work, but it's the fairest and reduces the likelihood of tenants that squander utilities.If you choose #2 or #3, there are considerations:Start with an average.

Cash flow is possible but for an average investor, it is very difficult for returns to benchmark.

What is the Average LTV you can get with a VA Loan ? 

Regarding the other types of loans, based on your explanation the conventional loan seems to (on average) have a lower down payment but takes into account the normal loan factors whereas the debt service loan doesn't but with a slightly higher down payment, proof of income generation through the property, and never being able to live in it.

The average tenant in Trenton City is going to have a sub 650 credit score, a lower wage or unstable job, etc.

If you are looking for above national average apartment occupancy, steady YoY rent growth, resident retention and a supply/demand imbalance, the Midwest is a great place to look! 

I dont see any mention on listings how much on average utilities are for the landlord.  

I dont know your Fico, but 8 1/4 at 2 points and 80% LTV with a only a one year prepay is probably decent to average.