Thank you - these are all things I wish someone had told me 9 years ago. I have come to follow these ways by painful trial and error, including the Interface calls (one of my favorite ways now besides event delegates)
I still hadn’t realized Get Player State was a bad idea. Somehow I got away with that one or resorted to looping through them to find a match to a unique identified I set up when the player joins. Not quite the right way to go about it but I was just trying to get the thing to work and there was no knowledge to be had anywhere I knew to look, to tell me otherwise how to get it working.