Please do not get this bird if you don't have experience with handfeeding. Trust me, you do NOT want the stress associated with it. It really is best to let the breeder finish the handfeeding and purchase a fully weaned bird. While more expensive, it could save you oodles in the long run.
As for adding another bird, are you planning on caging them together? If so, you might want to reconsider. First off, you take the risk of the two birds not getting along, which means you've just defeated the purpose in getting another bird. Secondly, what happens if they decide they like each other way more than they like you? Then you've lost the pet quality in your birds.
My suggestion? Hold off for now. So long as you have a TV or radio on for background noise, your bird will do just fine on his own. They really do not need another bird to keep them occupied...that is why they have toys