Don't worry too much about the anesthesia, it will be fine. You can't go into surgery all stressed out. However, I know it's normal. I had my rhino surgery two months ago. I was nervous about the final result and if i was going to like my nose, rather than the anesthesia itself. But also, I have had two surgeries before that(not related to nose), so I was familiar with the anesthesia.
You will be asleep and won't feel or remember anything. There is certain discomfort after you wake up after the operation. It might take you about half an hour to feel normal. But there is no pain virtually. You will do fine. Just remember to breather. Also, right after you wake up, you will not be able to breathe through you nose, due to swelling. And because of this you will most likely feel your mouth is dry - it will be a good idea to wet your lips. The first few nights sleeping might be challenging. But this is part of the process. Don't worry about it at all. We all go through it...
As far as sneezing - I was also sort of worrying about it, but i did not have to sneeze during those first two or three weeks. But in case you feel like a sneeze might be coming, make sure you sort of sneeze through your mouth, so that the air comes out of your mouth and not your nose. You know you shouldn't blow your nose for about a month or so, in order for the tissues inside to heal faster. You can sniff as much as you want, though.
Follow your doctors instructions for post-op care.
If you want read my post on here about my experience so far, I have put up before & after images, too: One week after Rhinoplasty Procedure
Good luck to you and let us know how your surgery goes...