Quoted:
Cell data is kinda sketchy for HD streaming. You may want to do some testing first. Forget about 4K.

Quoted:
The device is just a way to display streamed content on your TV screen.  You can do the same thing using something like a chromecast, Roku, or an HDMI cable running from your computer to your TV.  Kodi is software that can run on the firestick, your computer etc that can be used to organize your own content or stream content, from both legitimate legal sources or....elsewhere.  You have to intentionally configure Kodi to go search for specific questionable sources, it's not something you will do by accident.

It sounds like elsewhere has recently changed, I don't know the details of the latter.  Two people I know ended up getting notices from Comcast/content creators (in this case MTV) to "knock it off" in their mail after using bit torrent and other...sources to stream video.  The notices contained references to what they had sourced, one being Teen Mom 2 of all fucking things.  He admitted he did download a season of it via bit torrent for his wife.  Apparently Comcast has some sort of strike system and after X strikes they will cut service for a year.  That's what the notice said anyway.

In addition to having my own personal morals on the topic, I use my connection for my job and my employer pays for it.  As such, I stick to legitimate sources and pay for content if I want to see it bad enough.

Kodi itself, like a peer to peer sharing platform such as bit torrent are perfectly legitimate.  Things just get hairy when people use them to do things that are questionable.

This topic has been known to lead to lengthy discussions about what is legal, who is at fault, the host or the client, who the host is, considering it is almost always fragmented etc.