If the testing was performed by a home inspector, hopefully they are Registered Radon Testers with the State, and if so they are required to report it to DHHS on a monthly basis.  

What I would want to do in that situation would be take the performing asset to the local bank, get a 6% interest loan with a 15-20 year amortization, and then go to private money/HML for the rehab project, then refinance it when it's producing. 

As I am moving along in my education on RE I am starting to see a major need to track local market performance.

(Having a demo done tomorrow to find out the current pricing, I did this last year and turned it down because it was too much) And are they accurate enough when it comes to prospecting for it to be worth it?

That's not a small oversight when budgeting, so be sure to get the build costs to be accurate to the structure.Based on your example of 15 units, using 18,000 sq ft of GSF and a $1,000,000 estimate to build, you'd be looking at $56/sq ft to build.  

@Christopher DeitzI live in LA, I think master leases are a great idea, shoot for $500 a month positive, use a performance lease, owner gets paid when Rei gets paid

Finance is not real estate that most take lightly, while underwriting guidelines exist now for seller financing there is also a side that RMLOs probably aren't aware of, that is looking into the future as to the probability of a borrower performing  as  expected, obtaining other financing, secondary market underwriting is easy, predicting the future takes more skill and experience.Good luck :) 

I haven't done so yet, so I don't have a more accurate estimate, but I've been using 10% of rent as my estimate.What kind of shape is the property in?

If the total of mortgages, insurance and taxes is $20K as Ryan calculated, it is essential you accurately identify all of the operating expenses. 

This is true whether the IRA is a Roth or Traditional IRA, though of course the tax dynamics of each are different.The advantage of a Roth over a Traditional IRA comes with how long you will use the IRA before taking distributions and how the IRA performs.