But I'm interested in discussion that would fully flush out these issues.

wow this is wild, flush out the seller have them sign an offer to purchase ?

Current owners have been diligent in caring for the septic - regular tank cleaning, liquid detergents only, no oils down the drain, no feminine hygiene products being flushed etc etc etc.  

@JD Martin recently recommended Lowes Project Source Pro Flush toilets, made with all-Fluidmaster parts.

I can see the logic in this, and I am not trying to be a control freak, but I want to put common sense things in the leases like no flushing diapers down the toilet, not storing abandoned vehicles on the property, not storing items in the common areas, no hazardous materials, etc, and recovery of expenses related to various issues. 

We had an unused toilet, at the time, in the basement that was continually flushing that I didn't realize until I got my first water bill of $600.  

They make it sound, my take here, like they are so flush with cash that they are too busy to find lots to build on, so this program finds the additional land to develop.My questions were one, how do I know they really take my offer and not just circumvent my "finders fee"?

Doing drywall overhead is no fun, they are heavy and need to be attached flush to the current ceiling.  

CA is a giant toilet needing a good flushing, that's my opinion of it.

@Vladimir Khorikov have they tried turning on all the faucets in the house and running it for a few minutes to flush the lines out?