Although, it's very capital intensive and you have to rely on a lot of factors you can't control, contractors, interest rates, market shifts, realtors, buyers, appraisers, inspectors, material costs, weather etc etc.

@Nathan Gesner  is on point yet again, start with your basic estate plan first just like he did. 

Can you arrange for counters, floors, painting other “basics” without him tacking on his 20%?

It’s a straightforward process that offers benefits to both buyers and sellers.

Also these things cost money to sell - agent fees (5-6%), whatever your buyer is going to ask for at closing or try to hit you at during inspections (likely several thousand) plus taxes.

In many areas, there simply weren’t enough existing homes for buyers, which created a big opportunity for homebuilders.

My logic behind a area to hold is basically is in my zone of knowledge that means close in and in a  A-B area .BIG fish can have the whole USA in their  zone .Outside of my zone I am thinking flip it there are exceptions like all rules . 

I am training our son to basically do the rehabs but there is a learning curve.  

[2]   Do you know if the buyer is going to owner occupy or is it an intended rental?

Typically, you can only do one rollover per 12-month period (again, IRS Publication 969 has the details).In the end, having the option to invest your HSA funds is usually a better bet than letting them sit in a basic savings account.