So I want to make a Mongrelman. But How? (3.5)

So I had this idea to play a crab/lobster like race. The whole idea steamed from wanting to playing a melee Fighter/Barbarian while using a Crab style right arm to deal the attacks. But I dont want to make him to over powered.

Here is his description of what I currently have him look like. Large claw right arm, crab skin/shell on back/right shoulder area. Orc Eye with tusks protruding from the mouth, Human face. Human/elf lower body, Human left arm.

How would I decide his traits with such a flip flopped creature like this?