., the amount used to determine gain, or the portion thereof that represents depreciable basis) will equal the FMV at date of death.

Yes, I would ask for additional evidence to determine how much of that income is his.

What it will ultimately come down to is understanding your risk tolerance, determining your goals ( ROI, minimum cashflow etc) and building a strong reliable team. 

But if you live in more than one home, the IRS determines your primary residence by:Where you spend the most timeYour legal address listed for tax returns, with the USPS, on your driver’s license, and on your voter registration cardThe home that is near where you work or bank, recreational clubs where you’re a member, or other family members’ homesThese are simple tests, but it can get more complicated for a homeowner who has more than one home. 

They are paying me thru Zelle so my question would be, Is that going to be money I have to declare to the IRS?

Most do-it-yourself services will help you obtain this as part of the package they offer, but if you just file the articles yourself, you'll need to go through the the additional step of applying with IRS to get your EIN.

Most of your profits are determined when you buy, not by what you do along the way.

One article is titled: “Determining Maximum Purchase Price (MPP)”. 

Full doc (IRS taxes 2 years); or bank statement deposits for 1 12 or 24 months; or debt service ratio; or asset depletion...  

.- Once you've done that, determine which strategy is most likely to help you reach that goal.