(Assuming the numbers work)-Inquire with bank about their willingness to sell current note (depending on performance) at a discount.

It can turn into a legal mess with a PG and seller finance.The option gives you the chance to see how the property really performs at it's current base level to determine If you should walk away or you think you can turn it around.Is the seller wanting to owner finance because of most depreciation has been written off and they do not want to 1031 and instead take capital gains in small chunks over time given their older age??  

They could more accurately give you a ball park as every investor has their own idea of what a rehab should cost.  

More accurately, I started out in "war zones".

We've gone over this before: The 'Financial Analysis' tab shows the year-end financial performance of each property. 

I don't understand why you would use a non-subjective formula instead of an accurate ARV and Repairs calculation.The percentage off ARV doesn't mean much without knowing the repair costs. 

Who has used these and how accurate have you found them to be?

-When bringing individual contractors to bid on your project (plumbers electricians etc I recommend 3 prices from each sub, never go with the lowest price) they will be able to give you a much more accurate price.  

I believe I would like to be in the buy and hold area of investing, however I would like to perform 1 fix and flip over the next 6 months. 

Assuming this is performing loan, your annualized yield would be ~65% at that purchase price.