This is excellent advice through 4, but on 5 and 6

Establish a cutoff point where they're on their own - doesn't have to be stated, just in your mind at some point you'd say "OK, enough is enough". Usually, though, it's a moot point. They figure it out and move on and don't bother you.

On point 6, that only works if you tell the new employer before taking the job, and the cutoff point again is critical. You can't tell them after starting the new one. I'd ask "who do you work for, them or us"? We had a recent situation like that, with an absolute top-notch consultant but she was unreliable because we didn't know if she was working for us or still working for her old clients. She was independent for many years and it pretty much seemed she wasn't getting the "you work for us now" thing, and there was a parting of the ways.

The people paying you have to know they can count on you. And that means all the time.