Those 4 are the only female units in the game, which must mean Katauri are a bunch of chauvinist orcs.
The demonesses will decreases the morale of your eleven army, I think, unless you have tolerance level 2 (Mind), which requires a whole lot of runes to obtain.
I would definitely not recommend using the three elven females against black dragons, because these chicas have magic attacks and the blackies are immune to magic, so their attack will do very poor damage against them.
Hunters should become available after freeing the Elven Queen, though I don't know if this is always the case.