Well if you are brewing a traditional hefeweizen, you wouldnt add any other grains other than wheat and a pale malt
but, what you could do, is throw is some Crystal/caramel 60, like 12oz, and make it a dunkelweizen, or a dark wheat beer
richer body, little darker in color, and very tasty
as far as yeast, a bavarian hefeweizen yeast strain is going to be your best bet, and if I remember for the dry yeast packets they are blue in color, liquid yeast vials would be the WLP 300 or if you can find it, the WLP 351