How can we inform clients about the importance of meet and greets prior to stays?

Add it to your profile and DEMAND a meet and greet if you require one.

I merely add a sentence in my initial response to a client's request gently stating that I do insist on a meet and greet for new folks to give the dogs a chance to get to know me before I drop by. What I don't say is this is exclusively to help prevent them from becoming territorial or otherwise aggressive when I enter the home. You can certainly add info on meet and greets to your profile, and even mention that you require them, but I would still state this in your initial response to a request because many people won't read your entire profile.

I will say, when I raised my prices, I noticed a significant decrease in the number of last-minute requests I get, and people seem much more invested in doing meet and greets. There could be other factors at work (moving to a different state, switching from dog boarding to sitting/walking/drop-ins), but I felt it was worth mentioning in case it's helpful to you.

To answer your question about the importance of M&G's you can add a statement to your profile - but that's about it. Even for short notice bookings a M&G should be held or you open yourself to accepting a dog that's not appropriate to you and your home - best of luck.

As to you other suggestions - they are good