First off, FH+ was not "given up on". Simba, the creator of FH+'s computer crashed (Or something like that, too lazy to check the post) and he lost all progress on the game.
New Flying: I'd like them to make flying and dashing a separate button, flying is extremely slow. But they should make it more realistic, I've never heard the idea of a skydiving option before! :3
Tail/Head Movements: Agree with this, maybe a key for it would be nice. (Like unlocking the head and moving it wherever, there would be different keys somewhere else to move the head different ways)
More Actions: More battle positions would be great, I mean, headswinging isn't the most realistic "fighting" action. XD
Eye Movement: That wasn't a mod, it was emotes, and it's not gone. It comes in a pack with a bunch of very weird and amazing emotes I believe, but I don't have a link to it at the moment.
Good ideas! ^^ But sadly, due to the creator of THIS game being gone we can't add anything, since we need to source code to add new updates. But it's still fun to think of ideas. :3