[Nick_K]

Research /can/ be very useful. Magic is one area where you can get a huge edge over the AI. However, on small maps I've often defeated several AIs (On normal or difficult) before my research bears major fruit. Effective use of magic could give you a huge advantage, but I think you'll get a bigger edge from focusing on expansion at first. Independant heavy inf, priests and archers (pref longbows) backed up by illithids and (lots of) wine bags should be perfectly adequate to beat AI Ermor with, as long as you have enough of them and can field one or more big armies without being overrun.
Battle mages, summonings, SCs... these could all help a lot, but you don't /need/ any of them.