The most important question you can ask and investigate/confirm yourself.

In the design phase, I’m intentionally wanting to add features and value to later use as part of my long term funding strategy.

Give the property manager 7 business days to acknowledge receipt and confirm the termination date.

I contemplated the idea of just changing the design concept to have it be attached to the main home, but even in that scenario, the explicit CCR's against even renting one room seemed too controlling to be sane, considering that if this worked as we wanted, there were like 200 other nearly identical situations with lots with homes in that neighborhood that we would have just wanted to rinse and repeat that strategy.

Looking for feedback on that from anyone who might confirm or know otherwise...

First you’ll need an engineering design.  

Accounting, Risk Mitigation, Marketing, Advertising, Branding, Web Design... you get the picture.A lot of those things can be outsourced but you still need to know enough about them to make hiring and project management decisions.If you're entrepreneurial and a confident salesman (or quick study) then I'd say absolutely consider it.

Very helpfulRe: 15% it can be a good rule of thumb, but understand that every project may break that rule due to specific issues (title, environmental, local government, design, etc.) but yes your permits, arch, legal shouldn't be blowing up your budget at 25% off the bat.

I've got an architectural design picked out, a contractor selected, and I've got the family ready and willing to move into one of the units.

I needed confirmation.