[Endoperez]

Ambibate Nobles are comparable to MA Principes. 12/15 protection instead of 11/18, shield instead of tower shield, broadsword instead of shortsword, less morale and encumberance. I think they're rather good for EA. I might use Marverni Nobles if I was in a hurry, or tight on money. The Eponi cavalry look as decent as any non-sacred, non-knight cavalry.

The standard-bearers are vulnerable to both melee and missile fire, though, but you might be able to use your melee commanders instead. They have standard, except for Boar Lords.

The non-noble warriors aren't good. Berserker types aren't worth their price due to their attack/defence skills being lower and due to an inferior weapon. Slingers aren't useful after very early game.


EDIT:

As for Earth/Astral, the useful spells and items are:
Crystal Coin (+1 S), Gifts from Heaven, Golems, Gate Stone as far as artifacts go, and then all the Earth spells and the Astral spells. Earth Power gives reinvigoration, which can be nice even if the Druid isn't scripted to cast other Earth spells.