9) adding multiple ADUs or adding an ADU to a quad looses F/F conventional financing.

You can target lists through a multiple list source sites, skip trace those lists, then market to those buyers through cold calling, SMS campaigns, direct mailers, and/or door knocking; amongst other routes.

It seems like you have some very solid goals of multiple income streams, and a well calibrated risk tolerance. 

Your best purchase will be an acreage with roads on multiple sides.  

Would a bank even allow us to mortgage multiple buildings on a single lot without it being subdivided?

You will need to be ultra conservative on your numbers and have multiple exits.

So, why would they waste their time getting multiple bids when they already know the answer?

I had multiple applications and inquiries were still coming in.Also keep in mind your goals.

everything on and off market gets multiple offers almost immediately. 

I would rather not go to multiple lenders trying to figure out who does what if someone on here has had good experience with a particular lender already that does this type of loans.