Need for remaining house demo: roof, walls, mechanicals.

Additionally, whether you decide to pursue making this a legal unit, or part of a "Finished basement" for the residence; since the work was previously done without a building permit, the City can make you expose all plumbing/electrical/mechanical work to ensure it is up to code; or they can even make you rip everything out and start from scratch!

Fixed up the interior, mechanicals and roof.

As long as goals are aligned and there is a mechanism in place for adjustments as those goals shift in the future.

In essence, this is a one shot deal, so they will have no control mechanisms. 

In signing and opening of escrow I waived ability to file mechanics lien.Are you looking for something like that?

I am a mechanical/design engineer by day and primarily want to use this as a learning tool for me (for future BRRRRs) and hopefully help out of state investors.

Often they will not take anything up front.....they will expect a payment of some sort as work moves along though, not because they need the money, but just to make sure that you are a 'Good Customer'.Don't worry about the dreaded Mechanic's Lien too much, it can be removed by a lawsuit....but you hope of course that it will never go that far.....

We defeated the locking mechanism. 

I'll run down your list for emphasis...