Perhaps you are excellent at all four roles I outlined.

That said, long-term the appreciation you get in the Puget Sound region is superior to many other markets, so assuming you find an excellent property management company that is able to screen tenants and only put in very well qualified, vetted occupants and you experience limited issues over the holding period, you'd likely come out ahead retaining the Mill Creek property if your financially able to do so and still buy wherever you are headed out of state.

In the case of a syndicate, the LLC and its operating agreement help to formalize the legal relationship between investors.

How can investors build strong relationships with PMLs for long-term success in fix and flip projects?

Driving for dollars and attending local real estate meetups can help you find motivated sellers and build relationships.

I would recommend that you get @Brian Burke's excellent book The Hands-Off Investor, before you look at any more deals.

Communication, trust, and a good relationship.

I'm deliberating whether I should hire my neighbor (he just had leg surgery and walking with a cane) across the street to do construction because if the construction turns out bad, I strain the relationship with the neighbor across the street, and also whether I should hire my neighbor from another place who does the design because I kinda don't prefer he knows where I live (just because if the design turns out bad, I strain another relationship with him and exposes my address of where I live).

We've been using an agency in Zachary that we have a good relationship with.

I know how busy this will be, which is why ideally once we have 3-4 properties, the maintenance of the website, advertising, and property management will become my full time job (my wife will continue to work to provide some steady income during the transition)For your 4 questions - those are all excellent things to look out for and they are things I would not have thought to ask.