HoMM3 HD is a mod (add-on) for the game Heroes of Might and Magic 3.

The HD update has nothing to do with it; the problem is that in the latter case, HD is installed not on the full, normal version of Heroes, but on a damaged, cut-down repack.

1 - I'm not rushing with this; I'll do it when I have time.
2 - I don't know. Maybe... or maybe not.
3 - I'm not rushing with this; I'll do it for HD+ when I have time.