So, for example, if your interest in the property equates to $100k equity and $250k loan, you must invest at least $350k in the new property. 

The other side of that equation is the 5% interest.

I’m stuck finding a simple equation for owner occupying, what did you do for your first duplex if you lived in one half first?

The only thing I've suggested so far is to leave the realtors out of the equation to at least save that money.  

FHA, since it's such a low down payment, is going to bring PMI into the equation and that plus a high mortgage payment are going to put a real cramp in your cash flow (you should assume it will be negative in the IE)

You might be able to download this data as a csv from MLS and create an equation, but overall I don't believe that this information would be very useful because value of land depends heavily on zoning and location.

So with that being said, i can use this discounted scenario and put in equation that lends itself to a reasonable value.

2nd question - does anyone have an easy equation on how to calculate holding costs while doing a flip as well as what profit margin you look to make?

This clearly does not equate to a “Ponzi” scheme where new money is being used to pay off old investors.

That equate to a '66.66 times rent multiplier'.