HI R.!
I used to work with ENT Dr's for 8 years. I got to know all patients by name (and even knew their birthdate by heart) because they were in so often.
This procedure is VERY routine for any ENT doctor. It's very common for toddlers to have this procedure. In your son's case, this has been going on for so long, I'm pretty surprised it's taken this long for them to decide to have the procedure. Maybe they thought as he grew, the Adnoids would respond better, and the problem would "outgrow" itself. I'm a little "rusty", but I believe that's probably why they waited :o)
It's always scary when our children have to go through anything like this, especially involving anesthesia. I assure you, though, this is a very safe and normal procedure.
If your son still has a bottle/nursing at night, make sure his head is elevated enough so that his "neck/adnoid" area is above his chest. This way fluid should go all the way down, and NOT get trapped in the Eustachian tube. This should help for now.
I always "propped" an extra pillow for nursing/bottles until they were done, then I would remove the pillows.
Working with ENT's got me paranoid that my kids would have the same re-occuring problems, so I was over-zealous on things like that :o) BUT, I am happy to say that only one of my boys had a double ear infection and only 1 time. Otherwise they were both very healthy in their ears.
R., don't be worried. It could be the best thing for your son, and the never ending pain he may have now. If he DOES get tubes, then my biggest concern is summer is approaching fast. Is he a swimmer? If he is, then those "over-the-counter earplugs won't help him enough to keep the water out. Resulting in more infections. You should have "custom swim plugs' made for his little ears. It's very easy, but it can cost around $70 or so. I remember taking the kids ear impressions a week or so BEFORE their surgery, so after their surgery, they had their plugs ready. Because your son's age grows so much, the plugs may only last one summer, then they will not fit his ear.
Please let me know if I can help with any other info :o)
N.