Mileage.. would be a self employment deduction, if you didn't get reimbursed and kept track of your mileage I believe you can deduct the mileage cost use.

I would consider 675 for a long time tenant that has a great track record of paying on time.

You are probably better off tracking population changes and permits granted, projects started and projects completed.Even if you find a pattern, the extreme distortions in the market like abnormally low interest rates may make any conclusions questionable.I am not suggesting you do not try, as you will learn a ton in the process.

Track all of your income and expenses in some sort of report form and review it regularly with your employees or Team members that have the kind of talent you have looked for and have the ability to help you to possibly decrease expenses and increase income.  

In my experience, quality investors are the hardest thing to find without a track record. 

Once you get past a few keeping track of different keys is a pain and its easy to change the core out when there is turnover. 

These two numbers help me track where my leads are coming from.

I have been using the money we've been saving to invest in mutual funds tracking the S&P500, etc so that has definitely been good.

Start with a manual process, then automate parts, being sure to create a way to track the performance of each marketing piece.  

Glad to know I'm on the right track.