My son had his adenoids removed also. He had chronic sinus infections for about a year. It was an outpatient surgery so it was all in one day. We elected not to remove the tonsils as they were also underdeveloped and felt the added surgery was not necessary. We also consulted a few physicians to be sure. They said the same thing ... there is a "possibility" that they may need to be removed, they could not tell me for sure that in the future it would be necessary.
Since the surgery he has been very healthy and has normal breathing patterns, except when allergy season and colds get to him. I've also read that adenoids can grow back but haven't seen any symptoms of that.
About the surgery. Only one of us could go back so we sat with him in pre-op until he needed to go into the operating room. I carried him in and sat with him until they put him under, which was very quick. The thing that hurt the most and angered me the most is that I specifically asked to be in post op room so I would be there when he woke up. They NEVER came to get either my husband nor I. An hour or so later I heard my son screaming from the waiting area and they would not allow us to go back. I went back there anyway and found my son was scarred and coughing up blood and crying. It broke my heart and angered me immensely, especially since the nurses were not attending to him and he was all alone. That was the worst part of the whole experience. I will tell you that about 2 hours after we left that place and were home he was back to his normal activity as though nothing had happened.
I would suggest to you to meet with the surgeon and staff and go over in detail how the surgery will happen and when you will be allowed to be with your child. This is your child and you have a right to be there every step of the way. Do not let any physician ever make those kind of decisions for you. Its really hard these days and people in general are too trusting of physicians because we all feel like they should have all the answers but the reality is they do not. Trust your own instincts and everything will work out.
Hope this helps you.