Loved every second of that phone call! 

Ie if they pay it off in the first year its $10k, second year $8k, 3rd year $6k and so on? 

I'd definitely second house hacking with either a 2-3 bedroom house or a small multifamily.

Then include a clause as to what happens if they aren't and additional damage results.I'm curious if this house had a second bathroom and if they continued to use the tub after they found the crack(s).

Should I get a second lender to fund for the interest payments?

And congrats on your first rental property.Why don't you just do a JV with someone who has money to build the second 4 plex?

Just this month we closed on a second comparable condo, with 20% down to avoid mortgage insurance.Here's my big question:Should we now pay our future savings toward paying down the remaining 80% asap, or should I continue on toward a third condo with another 20% down, immediately renting it out and covering the mortgage payment, so on so forth... 

The second pillar is a good insurance policy as that cover the majority of your exposure.

One of my rentals is on a lot that should provide enough room to build a second 1000-1500 sqft home.

One of my goals is to have a second revenue stream so how should I go about utilizing and leveraging these two properties?