A:AnswerYes you can mount the tv. There were even spacers in the box the TV came in to use. I just set mine up on the entertainment center I have in the room
A:AnswerNo. And I don't know any TV that uses or support's mobile data protocols. Why would a TV need to use a mobile data?
If you're using mobile data as your primary internet connections within your own home, you don't need a 4K Smart TV, you need to upgrade your home Internet architecture.
A:AnswerYes, there is an Air Play capability as well as an option to mirror your screen wirelessly through one of the inputs. We use it to watch Acorn TV, the one streamer we have which doesn't have an app on this Samsung. (Could have subscribed through Amazon Prime but had a deal)