Yes, Now is a streaming service, but you can pick an option TV Guide from the top menu on the Now App and see the same live Sky channels that you see in the EPG.
In TV jargon, they are called ‘Linear’ channels to indicate that while they are being transmitted live, they may in fact be prerecorded programmes, e.g. The Simpsons. But some of them, especially on the sports channels, really are truly live.
Yes increasingly there are Now live sport streams that are only available on EE TV boxes via the Now app. This includes the options to watch and switch betweeen multiple specific tennis matches , additional F1 feeds , featured groups and holes in golf and additional championship football. Within the Now app these are known as Bonus Streams and are found under the relevant sport section in the app.
Just to confirm I was watching Sky Sports News live on the NowTV app. Not sure what Pause has to do with anything. I just pressed the Up key then selected the Subtitles option.
Pause gets you to a place where you can choose subtitles in the Now dialogue when watching On Demand.
I never found Up Arrow until @BillyM @mentioned it, though obviously you knew about it.
As this works for Live as well as On Demand, it is no doubt the preferred access path to subtitles.
I. Believe that any of the up/down/left/right and the OK button in the middle will bring up the change Channel/Subtitle screen in the Now app on the Ee TV Youview boxes