@Mike McCarthy Thanks for the insight. The points you make are valid ones, and it is the reason I want to know what can be done through either a bond or policy that could protect me to some extent from the potential pitfalls. In response to your questions, here's what I know...
What if the reno still takes longer and costs more? - This is an x factor. what is needed is insulation, sheet rock , and a roof. All wiring and plumbing are intact and in good order, up to code.
What if the house doesn’t sell? - This house is in a good area that once done should be well on par with other houses in the area, and market is strong near Austin, TX.
What if the house sells for 70% of what he thinks it will? - I can't speculate other than to research other houses in the area to get a feel for what the market will bear. If it takes a while to sell, I am fine with that.
What if he runs into an unexpected issue with the foundation/roof/etc? - Foundation is solid, roof is to be replaced, needs insulation and sheetrock.
Was everything permitted? What if the city decides it needs to be? - Everything is above board and permitted with the city.
I suppose it is about risk assessment, which is why I would like to learn more about how I can hedge my bet, to ensure against as many obstacles.