[Taqwus]

Folks with multiple melee weapons do get all attacks from all weapons, although if they're long weapons the unit/leader is likely to get an attack penalty unless he's unusually skilled at this (ambidexterity bonus).

IIRC, heroic/spell quickness essentially provides a chance to get an extra turn of actions for that unit, be it casting or moving followed by attacking or whatever, with the associated additional fatigue. It's not limited to a single attack etc. (Heroic and/or blessing) + (item or spell; does not stack internally e.g. boots of quickness AND jade armor aren't better than either one alone) quickness do stack.

I don't know how the Stone Bird and Astral Serpent work with multiple weapons/multiple attacks. Perhaps they act once per action, perhaps once per weapon, perhaps once per attack. Dancing Trident acts as a bonus weapon (no length/ambidex penalty) which repels well (length 5 or 6?) and gets one attack per action as well, methinks.

Now, multiple-attack weapons have a bit of a limit, IIRC, in that each action with a multiple-attack weapon must direct all of those multiple attacks onto the same square. Different weapons and extra actions caused from quickness can attack elsewhere, methinks.