Initially I was intimated, not feeling I was contributing much, but quickly realizing this would never materialize without my time and work.  

Like buying, leasing is mostly emotional and driven by the women (if it's a couple).

John Jackson I've been reading up on some of your material and it is great stuff.

I did  extensive research, contacting multiple construction companies, estimating materials + labor.

I need to do inspections, I may need to line up contractors, make material lists and other things, but I can do my part pretty quickly.

I am thinking of offering my services, paying for the higher end materials, and pulling all the permits to make this all done by the book.

My thinking was driven by the idea that millenials are a more social demographic than my isolationist gen X people and that they are having a hard time affording property in our crazy market.

Obviously it's very market driven, here I've paid 0- $200 depending on the level of detail and the complexity of the work. assuming he is talking 2% if 15,000, $300 isn't wild but could certainly be beat. 

I ask this because I do not have a firm grasp on the subject and would love to know more. any suggestions  for reading material ?

As for the sinkholes, anything related to the drain pipe, including holes caused by loss of material, is the responsibility of whomever maintains the storm sewer system.