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

I am closing on my first property in the next few weeks and I am trying to get my spreadsheet setup for tracking ROI and other metrics.

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

@Bob Asad investors in high-cost areas do this all the time, but I wouldn't.They are betting on both value & rent appreciation, but it is speculation.

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.

Better than the alternative of having a line of credit at 12%, the 2-3% hit in spread is lower than a 5% increase in cost of capital in my opinion.

I often refi people with a 0.5% rate drop and no closing costs.