Still yet, a gamble, no doubt.

Right off the bat you have an accurate accounting from the moment you began your business to the time you call it quits of every dollar you invested in your business, to the time you sold every property.  

@Alexander FeliceGood point about the 5 closest friends, that sounds pretty accurate.

I don't think it necessarily looked down upon, but while you can calculate cash flow pretty accurately, it's hard to calculate appreciation.

With regard to number of days rented, just trying to get an idea for each area so we can accurately project ROI.

Yes, DC has the school choice option, but it is a gamble, a literal gamble.

The data on pre-foreclosures is rarely accurate.

How accurate is their data? 

The appraiser's opinion shouldn't be worth much because YOU, the investor who intends on being the successful investor, will make sure that you can appraise it more accurately than the other guy.This seems like the kind of deal where you can say "$270,000 and 7.5% and I will do this deal", and the dude will probably agree to it.

Sub-meters are helpful for more accurate bill backs, but you will want to have a set time to do it because it's unlikely the electric service will track this for you.Usually with a utility bill back there is an addendum that breaks down how the bill back is calculated.