Here is a good website that can answers some of your questions:
When a C-section is necessary, Whelping Puppies
Many females will be slow to get their milk after a c-section so it is always wise to be prepared to bottle feed in case she does not get milk or is slow to get milk. I have heard of a few cases where the mom never got milk after a c-section. One of the biggest concerns with a c-section is that the mom might reject the pups. I have only had one female that required a c-section and that was many years ago. She had one big pup in her and she did well at raising her pup.