Some of these expenses can be determined and others are "best guesses". ie, for taxes, you can find the tax rate on the county website and then plug in the purchase price as it may adjust to that.

You bet! 

Appraisers make adjustments to subject properties based on the difference between the comp and subject property.

After the 2009 debacle.......do you feel that investors are STILL doing adjustable rate mortgages - knowing full well they'll reset?

As for vacancies, I was following instructions but I can adjust to 8-10%. 

This is your adjusted cost basis. 

Now I had just had a newborn at the time and quitting and betting it all on that career path was not something I wanted to gamble on my family's financial future.

@Sattir BittiSome considerations as you do what you are planning to do.If you are currently itemizing your deductions, you may see an increase in your taxes if your mortgage interest is reduced.Your 'appreciation' is taxed when you calculate your gain.Gain is sales price less selling expenses less adjusted basis.Your suspended loss may get released upon sale of the property.Best of luck

Or you could look at your last tax return and that will tell you the adjusted cost basis of property C.

For example if a sale had $5k in seller assist towards closing costs an appraiser would want to adjust for that because the seller received a net amount that is less than the sale indicated.