How do you go about deciding whether to add large scale amenities vs another building or using the space for something similar. i think even if the foundation is usable from for the ADU, far from a certainty, that your cost estimate is off by approximately a facor of 2 (meaning it will cost close to twice your estimate assuming you are not doing a lot of the work yourself).  

You plan an active role so it should not be as pronounced as a hands off ADU addition.  

This is how you get ripped off folks.

Are getting it off market and the numbers make sense.3.

There are way too many varibles and you'll either end up way off or get overwhelmed and become paralyzed. 

I will say I was quite put off.

The refinance will get our down payment back, along with the current mortgage and renovation loan paid off.

If not, you may be better off just standing pat.

Where do I start and what makes them "off-market"?

I am in a low tax bracket as I take alot of write offs.