The down side of a neck dissection is, well, neck surgery. Mine was bilateral, even though there was no evidence of diseases on the left. I had a 3 cm node on the right. The neck dissection was the first thing they did.
The surgery itself was not nearly as bad as I thought. I was taken up to the ER about 4 PM, and was in my room by 6:30. They had to take special precautions with me, because I had a 2 level neck fusion 2 months earlier. On the bright side, they had an incision line to start with.
The first night I was pretty much out of it, with morphine IV for pain. However, next morning they switched me to less dramatic pain meds. Tell your relatives to be prepared, as they usually do not put a dressing over the incision. I had 3 drains in. By noon of next day, I was up and around, eating regular diet, carrying my drains with me as I went. Depending upon whether they want to discharge you with drains or not, anywhere from 2 -4 nights in the hospital is customary.
Long term, expect a "wooden" feeling in the neck, and tightness as nerves start to reconnect. This will be exacerbated by radiation treatment. All in all, very doable though.
Let us know what else you need to know.