Currently they have average finishings for the area.I have an idea on the rents but would like to hear what other people are currently renting their units for.

It seems like though they are great investments, though there are not too many people who actually dive into a private placement like this. 

Are you talking about permanent movers, or those on vacations of some sort, or people who are temporarily to be housed due to an emergency and then intend to move back to their old stomping grounds?

I understand that I can deduct mortgage interest up to $750k on my personal residence.

People do it, but my suggestion is to not screw around with federal programs.   

Google Sheets is a great tool for multiple people to track expenses but as they say "garbage in garbage out" so see where the breakdown is and shore that up. 

As for the development fees/taxes, my understanding is that it only applies to new construction with the intention of selling or leasing should they not contain enough affordable housing units. 

Life is too short to have to put up with these kinds of people in this business, even though this may cause you a short-term interruption in revenue. 

My advice is to connect with right people.

While starting off with this strategy you could also be studying more about value-add options and start attending meetups in your area to get an idea of what other people are doing.