The determinations of whether such investment income is considered to be ordinary interest income, net rental income, and/or capital gains are much more involved. 

@Patrick Soukup,I don't know anything about appealing taxes in your area, but my guess is that a third party appraisal documenting the recent sales price would be a great determination of FMV. 

I'm looking to make an offer on an off-market BRRRR deal.  The property has 2 separate buildings on a (small) parcel that normally would just have a single, detached home.The front "normal" home is your typically cook...

So I opened Excel and had no idea what to do, so I went to YouTube....there IS A WHOLE PART OF THE INTERNET DEDICATED TO YOUTUBE VIDEOS ON MICROSOFT EXCEL. 

You really did not provide enough information in order to make a determination about what is best to do with this property.

For example, if I rent a property to my tax practice, that property is considered a trade/business (whether or not it otherwise would have qualified as such) and may be eligible for the deduction.3)Third, they tell us that to determine what is a “trade or business” (I am just going to use the term “business” from now on), we can only look at law under Code Section 162.So what does #3 mean?

At least until you have the property inspected to determine the current condition and life expectancy of all major components and appliances.  

How do we determine her niche and how she could add value to the business?

with that info I should be able to more accurately determine what's a good sale price for the building.when I was looking into cafes/ coffee shops before, I read a lot of the facts about how many fail and why they don't work etc...

Have you determined any of your criteria yet on those projects?