We don’t plan to leave jobs and live off of the portfolio but have it as a wealth generator aka hedge against future risks

At a certain point it becomes a lot of work but you can outsource a lot of the work by hiring VAs which is way cheaper than a management co (definitely not as hands off though) 

If you prefer to be hands-off with full-service management, then I'd plan on paying around 20% commission as that's pretty common.

If you operated a business, even without an LLC, you may potentially be able to write off certain expenses.

Perhaps it is better to cap off the chimney at the top, or inside the fireplace and just make it decorative.

In general hands off ADU additions cost more than the value that they add.Have you looked into what the garage could rent for as a garage?  

It just obviously won't be market specific.On a personal rezoning I did for a house hack new-construction triplex, I was asked numerous questions about how many bushes and trees I was going to plant.

First, please do NOT think you're going to generate enough cashflow to live off of within 3-5 years. 

It just seems like the guy tasted a little bit of fame and success and decided he could make more money with these get rich quick programs and ripping people off, than investing in real estate itself.

He kept in touch with local contractors, and one tipped him off about a homeowner who ran out of funds mid-renovation.