I started at age 38... now we have two SFR and two duplexes free and clear plus one SFR and one eight-plex financed with conventional loans that are performing well within the perimeters of the 50% rule.

The previous owner will be of no help because it is not uncommon for banks to switch servicers to handle the non performers.  

OR you can get approved and inspected to perform them yourself in a room with locked file cabinet, etc.

A lien only makes sense if it's performing and priced less than 20% I think.

Kelly,In my experiance, if you have the money for a DP (20%) the banks will go ahead and count the rent on a property towards your income, otherwise you will have to show some track record for that property's performance.  

In many cases it would appear the cost of implementing the B-Dry system was not significantly cheaper than sealing and waterproofing the foundation from the outside - which is the better way to do it.Perhaps attaching the base plates to your slab won't make a real difference in the performance of the warranty.

Each performing note is selling for 80% of the value.Each non performing note is sold for 20% of the value.Are these typical values?

I believe it to be highly beneficial to perform real estate investing activities. 

I'm fortunate enough to have a tiny window of time to try and perform some due diligence here.

If you fail to perform he has recourse under that sale of the LLC interest.