I haven't had twins, but I do know you need a Dr you are comfortable with, not one who isn't willing to explore other options. Keep looking around, after all, you wouldn't hire a nanny who would do things you don't agree with, and your OB/GYN is really the first caretaker of you and the babies.
That being said, you can't close yourself off to the possibility that it might become MEDICALLY neccessary to have a c-section. If yours, or the babies lives are in danger, you want a Dr who is willing to look at all the options, and take the neccessary action.
Also, breastfeeding is not out of the question with a c-section, or with twins. The football hold is perfect for keeping baby off the tummy, with the added bonus of being able to hold two at once, with a little help from Daddy! I would contact someone from the La Leche League for help/info.
Good luck, and congratulations!