I dont want achievments to be account-wide, at least not automatically. Because the OP is right: The game encourages you to play one character and my guess is that thats partially because its so story-heavy. The story of that one character matters - and earning certain achievments is part of that characters story. They shouldnt be just dumped on any new character - if someone wants that, I dont midn giving them the option, but it should be something you have to turn on manually, not something that just happens.

All mounts and minions that involve promitions or the mogstation should be account-wide, agreed. But, again: Not agreed for any mounts you earn ingame.