To minimize taxes, ensure all deductible expenses—such as materials, labor, and loan interest—are properly documented.

Get something durable in a color that does not stain easy and a material that can be scotchguarded and you will be good for several years.

Biggest things you’ll want your cpa to guide you through;Material participation- there’s three tests; 500 hours; 100 hours and more than anyone else’s time, and substantially all the activity.

It's always better to check with your brother's CPA since he has all the background, but I would say short-term rental with material participation requirements met by your brother, then do cost segregation.

Pretend your getting the hardest rain you have ever seen and imagine where the water is going.I would also keep an eye out for sewer lines and type of material.

Material participation in the rental activities still required. 

They try to get investors to focus on the ROI numbers they promote, not comparable sales.

A ton of house hacking material on there :) 

It could be anything... a mistake in estimating, a cost overrun, or something like the place burns down and the insurance wasn't properly taken out, or theft (of the money outright) or theft of materials along the way.    

Perhaps you have coverage for the replacement value BUT the insurance company when calculating the replacement property uses modern building materials like drywall but your original house had plaster which is much more expensive.