brown and white stock questions

[gotsmack]

I have some questions about making stock:

1. Why do you blanch the bones for white veal stock but not brown stock?

2. Is there a taste difference between white and brown stock prepared with the same ingredients?

3. Can i get white stock pretty close in color to brown stock by adding in burnt onions and some onion skins? Or will it just look like dirty stock?

Thanks.