Im a new player to the ancient/medieval period (So one success for FOG's attempt to get new players interested in the period) and my knowlege of the period is limited to what interests me and what wikipedia has online

Im thinking about starting some armies and wondered if anyone could give me some advice as to how easy these armies would be to play with.
I was thinking about a greek hopalite army-I assume Athens-Undrilled average troops-Numbers advantage
Sparta-Drilled superior troops-Small elite army
Thebes-Drilled Average troops-Middle ground
Can these armies have Cavalry? I was thinking about a Spartan Army due to less figures to paint.
I also have an interest in the Crusades and would fancy an Arab army, maybe with crusader allies at first. Do any armies of this period use Camels? I think camels are cool

Ive also been thinking about a Viking army

Many Thanks
Conrad