When determining an accurate ARV do lenders appraise based off the 50% rule or the actual expenses paid in the prior year, IE: tax returns?

When practicing, don't worry so much about becoming accurate with the numbers, be more concerned with learning the process and calculations. 

As long as your Comps are accurate it could be a decent deal, but if the pendulum swings to a $290k sale price, there may not be much profit left.

Should I expect to pay a tax expert to give me a more accurate sense of my situation? 

Assuming that the appraisal is accurate, there's nothing wrong with this.

One thing I really do recommend is talking with an experienced attorney to get an accurate idea of the exposure you face.

Is there a more in depth guide or explanation on the ins and outs of these calculators and how to gather accurate numbers instead of just copying what Brandon does in his sample analysis's?  

Is it pretty accurate?

Property Tax) is accounted for accurately, or is this something I should be verifying and plugging in manually?

He wanted to list at 159,900 and I thought 139,900 was a more accurate price.