Welcome, Doublehex!
Well, if you want to know more about Oddworld races and the lot, I would recommend
www.oddworld.com, or even better, the Oddworld games themselves. If you know how's it going between the races and all, you will do fine. First, you better just join in an RPG, then you'll have experience and you can create one.
Have a good time at Oddworld Forums.