Vet clinics generally give advice when they give you your cat back after the operation.
I can't say the anaesthetic is not dangerous because any anaesthetic comes with a risk, even human anaesthetics are the same. However, they are very safe. A vet practice will do thousands of these operations a year and the vast majority have no complications. Having a pet get into difficulty is every vet's worst nightmare and we generally do our utmost to make sure it doesn't happen!
If there are any stitches protruding afterwards, she may need to wear a Buster collar until the sticthes come out. However, many vets now use dissolvable stitches and bury these in the skin, so no collars are required (phew!). She will have just had a major abdominal operation, but will have been given painkillers before the operation, and you will be given some to take away with you afterwards, so she should not be sore.
Feedwise, she may not feel like eating when you get her back, but you can offer her small amounts of food the first night, then build it up to normal over the next day or so. You might want to keep her inside for a few days until she has fully recovered.
She may sulk with you when you get her home, but generally they get over it soon enough!
Hope this helps!