If it requires a 15% down payment, then that wold explain why I hardly see this talked about here, and would make the FHA 203(k) the obvious choice for me (starting on a limited budget)

woody - 1st option  would be to  try to get a " cash out " refinance on the Seattle  rental  property ….2nd  choice  would be an  owner occupied  purchase loan for the CA  possible  property   ( get pre approved for this idea )  if you are unable to do these options because of  whatever the reason ….I am not certain about the " collateral loan "  idea / question

You have 3 main options assuming you want to keep growing.1.

The main question I ask is how long this growth can continue?

My next choice would be a Turnkey  Property that is renovated and managed by some other group of people and your only duty, after your original inspection and an evaluation, is to get a check from them each month. 

@Jorge Pena the main reason to sell is because a lot of bad stuff can happen with rehabs of this size.  

The decision to sell or hold is totally a personal choice.

Without a family/girlfriend you have the ability to make all the decisions/choices you want right now.

Here are my main questions:-Should I be getting an inspection report and/or an appraisal from her?

You have no choice in the matter .