1- They are not 4 years ahead of us, they are at best 1 year ahead and should remain like that or even see it reduced to 6 months, remember they only had 2.0 early 2016 (if i'm not mistaken) and we got it early 2017, yes they are much older but we already had a huge catch up. Although i do agree we will never catch up to them, again 6 months delay at least. Even the Taiwan version is around 3 months behind the CN version.
2- Facebook version is the Taiwan version. The one we actually seem to be following to a higher extent, but even they follow the CN version for most of it, so you know...
3- Unless they add the Boruto stuff to the game, they will run out of content soon, maybe 2 more years and its done, no source material no more game. they are already at the fight vs madara in the shippuden so its close to an end.
4- The Asia server we have are still in English, just placed at a better host spot for them, which makes sense, although its still the English version. Dont know why most people call us the North America version, when it is just the English version, no matter where we are in the world.