Dolby Atmos advice

Hey everyone. Pretty much an amateur when it comes to AV Tech. Looking for some advice and answers to questions (Don't even know if I have the right questions).

I just upgraded to a 4K Apple TV. I have a Philips 65" 4K HD TV. What I want to do is add a sound system that includes Dolby Atmos. I'm thinking along the lines of a soundbar, I have a small living room and an even smaller budget. I've tried reading a lot of the stuff floating around but I'm still confused about some things.

My first question is: if The Apple TV box has Atmos and I purchase a Soundbar that uses Atmos, am I correct that the TV does not have to support Atmos? Does the soundbar extract the information from the HDMI in for the sound and pass the 4K video through to the TV?

Will the soundbar handle the upward speakers fine if it is sitting on the TV stand. or does it only make sense to mount it on the wall above the TV?

How good will the sound be with just the soundbar and no rear surround sound speakers?

Finally, is there anyone who is currently using a soundbar with Sony Atmos and the Apple TV 4K that would recommend the system they are using?

Any and all advice is welcome. As you can probably see, there is a high level of ignorance here and I'm hoping you can educate me or point me to a website where much of this is explained in simple terms.

Thanks