Rentometer is another resource for comp rents.Trulia has a "local info" section with heat maps to visualize data like crime and demographics.

I would also suggest conducting demographic research.

I used to use $4300 per unit per year on a standard 80's construction building with standard landscaping. 

Den could be 4th walk-through bedroom.Home was completely renovated recently with amazing landscaping in a  great neighborhood. location in Donelson that is convenient to downtown, airport, opry-mills, briley parkway, I-Available early to mid DecemberRent $1395Deposit $1395

Investment property is depreciated over 27.5 years for the home, 15 years for improvements (fence, in ground pool, landscaping, etc), and 5 years for personal property (stove, refrigerator, dishwasher, etc) You can't depreciate the land value.

The biggest factors that affect NOI are jobs, supply, and demographics. 

The demographic of the neighborhood is changing and has been for quite some time. 5 to 10 years ago it was scary.

From what I've seen, townhouse association dues tend to be higher than single family homes because the townhouse dues cover exterior of the building, roof, landscaping, pest inspection, etc. 

Once the deal closes, the same agent, or another agent in the office immediately begins managing the turn around, doing capex for visuals (signs, landscaping), while managing the capex for per unit customization as tenants express interest and sign contracts.

I did not understand demographics, subdivisions, cap rates, or development.