A:AnswerWith the GPS version you can download music onto your apple watch and directly connect your AirPods to the watch to listen to music with out your phone present. It's a great feature if you want to go out for a run and have a playlist that you want to listen to without your phone with you.
A:AnswerThe gps only watch can work like a phone only if you have the phone near you. You and answer phone calls and text messages from the watch as long as you are near the phone. If you get to far away you will no longer have many feature of the watch that would require data (weather, news, etc)
A:AnswerYes it does. Recently purchased Apple Watch series 3 (gps) 42mm for my wife about 3 weeks ago. Works great with her iPhone XS Max, no problems at all.
A:AnswerI find that it disconnects after about 20ft or so. I usually have my phone in my pocket or on a table in the same room and it works just fine, even in large spaces like a living room or across rooms in the house it is always connected.