that is requiring me to estimate Capex (which for this exercise includes maintenance) across US cities.

Only the good tenants should be able to legally exercise their right for "lease for life," and because they are good tenants why would you want to get rid of them or why would a bank not want to finance a building filled with good tenants who take care of the property, follow the conditions of the lease, and pay on time?

Some examples of potential future drivers will be: something similar to what Bush did when he signed the American Dream Downpayment Act of 2003, China easing up on Capital Controls (this would be a great sign, but with trade war and China's issues with their own economy I seriously doubt this), IPOs over last 2 years creating much needed wealth for employees (takes 12-24 months for them to be able to exercise stock options), a dot com like bubble in the stock market (I think this is most likely scenario given stock buybacks and QE and I won't be surprised to see stocks doing something absolutely unbelievable over the next 1-5 years similar to 97-end of dot com bubble), or heavy doses of QE and easier access to credit for most people.Working in the Bay Area, we saw first hand how many buyers were foreign and how many paid for houses in cash without even looking at the homes in quite a few cases. 

Some contracts have enhanced death benefits with fancy features for an additional cost.  

Does anyone have other suggestions for those valuable skills that I could do part-time while building my portfolio and enhancing my REI skills in general?

Also, along with podcasts, listen to as many audiobooks as you can while you drive, work, exercise, etc so you can start to figure out what niche you'll want to focus on.

Some HOAs are rewriting their bylaws to prevent owners from exercising this option which can be much more lucrative than a long term lease.

The object of that exercise is to minimize change orders ($$$) and to be sure that all three contractors are bidding on the same specs.

And it sounds like the bank often won't even exercise their due-on-sale option. 

Just like a bank loan they are responsible for all maintenance and repairs (because they are buying, not renting)Lease Terms: Purchase price when they exercise the option: $150,000.Monthly payment: $1,250.Non refundable down payment: $10,000.