Francesca - don't you wish there was a magic formula that said "this is exactly how you should be treated"? Unfortunately, there isn't.
I had exactly the same diagnosis as you, and was treated at MD Anderson, one of the top-notch head and neck cancer centers. They told me that given my clean margins, etc, that no radiation was necessary, so I did not have any. Do I sometimes wonder if that was the right choice? Yes... but yet I am also thankful I did not have to go through the radiation... and so far, I am doing well...
I know it's overwhelming as you look at all the information, but it is better to be well informed and also to sometimes question your physicians - they are not God and don't have all the answers, either...