Install new tar paper, shingles as well as vent as per instructions.If this is the first experience you've had with repairing roofs I would definitely consider having someone do this for you.

We’re getting a small shopping center installed supposedly by the end of the year (Marshall’s, Tractor Supply, Grocery Outlet) plus investments in a second “downtown” strip. 

You would add value to the unit if you could somehow install a window.

Additionally, the costs on installing parking meters please?

House is rented out regularly but also has a 2nd homesite that has a septic installed & perked for 2 Bed.

I just recently saw a similar post asking if installing PickleBall courts added to ROI.  

A DIY way of starting your investigation is visit the building department and see if they have any records for the property on file.

Understood that DIYing something that I don't do and saving $7 per month (that I'm charging the buyer for anyways) could blow up in my face if there are unforseen results in this process.   

The second bucket is jet clean it twice a year for $300-$600 and install a flapper valve that prevents it from backing up.

Unfortunately, most small landlords and especially DIY landlords fail at this causing problems in eviction court.