I am considering going this route with my unit and would love to hear about others experience.  

What I was thinking to increase cash flow would be to mid term one - two unites.  

Like I said, my approach is just about the opposite of everyone on here, but I can tell you that two of my paid for renovated units cash flow more than your 12 units do and I don't worry about making any of our payments and managing 2 units is way easier than 12.

This criteria is for 1-4 and 5-8 unit programs.

One unit is vacant and the other is rented.

May,If you are going to target Maricopa I would suggest focusing on 2-4 unit multifamily rentals.

Are all residential buildings (1-4) units taxed at the residential rate even if they are used as an investment?

If you try to find a deal that cash flows while you're living in one of the rentable units, you'll likely never find a property.

If you are looking for cash on cash returns as your spreadsheet suggest, there are much better deals especially if you look for 2 or more units. 

We subscribe to a market research platform called Yardi which only provides information on multifamily properties 50 units and larger so if you are invested in a property that is 50 units or more, I would happy to provide quick "back of the napkin" valuation and methodology.