The difference would something like that between a mechanic and an automotive design engineer.I don't think the law "requires" you to take every expense or deduction, it allows you to do so.

I pulled records and it appeared that although his permits and designs expired by the time he was listing property, zoning stayed as C-P permanently.

If you want to learn more look up architect Oscar Newman, Jane Jacobs' book the death and life of great American cities, broken window theory, and CPTED (crime prevention through environmental design).

for example if they had judgements, liens, mortgages, pending law suits, or mechanics liens.

I use Chief Architect every day with my clients (I'm a kitchen & bath designer).

If the bootcamp was designed to make you a better rehabber or to improve your skills in some aspect of your rehabbing business, then the cost is deductible. 

Dark wood floor, white trim, "Designer White" (or similar) walls.  

See if there is a website designer in the neighborhood who would step up to the plate and do some of the technical work gratis for his/her own benefit of improving the area and marketing by example of what he/she can do.

The Solo 401k is designed for those who are self-employed or own a business without any full time employees besides owner and his spouse.

It seems easier for a professional inspector to find the problems with an apartment building than a mechanic inspecting a car, since so many vehicle systems are sealed.