My son, who will be 10 next month, had his removed on the first of June. Now, this is after having an eardrum replaced the May before which entailed the partial removal of the ear and then sewing it back on. I LOVE Dr. Mark Brown in Arlington, but could have kicked him when he said the pain would be worse in front of my son. With the surgery on the ear itself, he was in agonizing pain for days and days. He and I both almost backed out of the surgery. However, it was supposed to help the ear situation so we forged on.
To prepare we stocked up on popsicles, pudding, jello, etc. My son never ate one popsicle. He said he felt like he had something stuck in his throat (swelling) and that it only hurt a little bit, but not bad at all. The day after surgery, he asked if we could go see if we could find a yard sale or two. However, he tired quickly and wanted to go home. So we did.
When he first started coming out of the anesthesia, he was VERY cranky. I was prepared for this from previous surgeries. He also threw up a stomach full of blood. I was NOT prepared for that. The doctor told us that about the third day to the end of the first full week, after surgery, was the timeframe when complications usually arose, if there were to be any. My son did wonderfully. He was also very quiet for several days because he felt like he had something in his throat and it "felt weird" when he talked, so he just didn't.
Really all you can do is be prepared with comfort foods and the pain medications the doctor will provide (get these before the surgery so you will have them when you get home because they cannot release from the hospital/clinic within and hour of patient receiving pain meds). Be prepared for her to be cranky and even downright ugly when coming out of the anesthesia. Also, you might want to have your ENT explain to your daughter that the pain meds that they will receive at home will NOT make her feel like the anesthesia or the pain meds from the hospital/clinic. My son absolutely refused to take any meds (even after the ear surgery) because he thought they would make him feel like he was out of control and detached from himself. There is no reason to be in pain when there is relief available. Besides if you lose the pain, you can relax more and heal more quickly.
I hope some of this helps.
On a side note, had I known that the adenoids sat on top of the other end of the Eustachian tubes, he would have had them removed YEARS ago.