With nobody able to see the unit in person, I had no competition negotiating and was able to get the house for over 20% under asking whereas it should have sold for full asking or slightly over on the open market.

I highly recommend that you utilize a low down payment loan (preferrably 5% down since it has less closing costs, you can get out of mortgage insurance once you hit 20%, and you save your FHA for another purchase) and move into a 3-4 unit property.

My real estate CPA has done several cost segregation studies for me and my clients.  

A good PM will keep you out of trouble and typically make you more money than they will cost you.

I didn't know the 70% (and then subtract out repair costs) rule.

If you plan to be there LESS than 7 years, then I might consider NOT BUYING because if prices stay the same it will take nearly that long to pay down a mortgage enough to cover commissions and closing costs to sell and break even. 

There are also additional costs of operating and maintaining an LLC, like separate bank accounts, annual report filings, tax filings, etc.2.

I have a tractor and have successfully fed wildlife before doing this.However, there is not a lot of margin to make a profit as I see bare land selling actively in MLS listings for $2-4k more than what it will cost me to buy the tax sale and do a quiet title search (likely $3k apiece). 

I would like to find out what are some good websites with calculators you use to calculate rebuild cost, so I have a better idea which replacement value is reasonable.

You can definitely reach 5% - it'll just cost you north of 10 points.