it is not user friendly at all.

ADU increase value less than the hands off ADU addition, but a developer is not a hands off ADU addition.Thanks

You can read about the differences here: Cost Segregation Study Approaches ExplainedLet’s first start with what the approaches:Detailed Engineering Approach from Actual Cost RecordsDetailed Engineering Cost Estimate ApproachSurvey or Letter ApproachResidual Estimation ApproachSampling or Modeling Approach"Rule of Thumb" ApproachSo which of these approaches is required by the IRS?

The set up is the easy part, it's just figuring out what you both like/enjoy.

She is not in a position to lend a personal loan to me. 

It does not matter if you find the single best market in the US.

A quick look at VRBO shows over 300+ listings so there is competition.

I set my rent standards a little high and realized that rent is actually not that high.. we have a morgage on it and it looks like the house is selling for more than we originally paid 4 years ago.

Is there a strategy to do a BRRRR with little to no money out of my own pocket?

not everything is 1:1.