Well Blizzard tried WoD without flying and received a big backlash for it (on top of WoD itself being unfinished and short on content), so Blizzard made a compromise with the Pathfinder. The reward for it is Account Bound flying.
Balance possibly.
Asmongold is just the Kayne West of WoW. That’s all you need to know.
Well yes and no.
Yes, the engine and some bits of the UI are different, as well the batching, resulting some of the spells being bugged out, as well as bigger servers and some things like the black lotus (i think) being changed around, but for the most part, no, it’s more or less the same as vanilla.
The only thing that is different is everybody knows what to do in classic now since it’s pretty much the same game from 15 years ago, thanks to the information from private servers and such.
Well that’s entirely up to you. 