Hi M.C.
I too had the same diagnosis as you (but in the right tonsil). when I went in for sugery I did not know (nor the doctors) what kind of cancer I had. Only that cancer cells were found in an enlarged lymph node. My doctor removed my tonsil as a guess because no primary tumor was seen. It turned out his guess was correct and he commenced with a radical neck dissection. Since I was still asleep I never had any time to learn about my surgical options. I will strongly suggest you learn ALL you can about the side affects of each variation of surgery (there are many variations) and of course the expected sucess rate for each. The side effects of the complete radical neck dissection can be significant. My shoulder will probably be a constant source of pain for the rest of my life (this is because of a nerve that is in the same path as a large number of lymph nodes) rather than carefully seperating the nerve thay just cut the whole works out. Since I was relatively young at 40 and since I am optimistic about my cure, I might have to live with my bad shoulder for another 40 years! Naturally If that pain is necessary to live then it's not so bad. If I could have done it differently and survive without the pain that would have been better.
Like wise what ever you can do to protect your saliva is worth doing. Not having much is for me the very worst side effect (though thankfully just enough has come back so that I can talk without a constant supply of water). Once again if it is necessary to survive then so be it, but explore every option with all your Doc's and call in for third opinions. This is something you will have to live with. Make sure it is not just because it is convenient for the Doc. I wish I could do mine differently but that Isn't going to happen.
The effects on teeth is a topic I haven't seen (nor looked for) on this site. The past standard was for removal of all teeth in the radiation field still is if they are in poor condition. I have all of my teeth including wisdom teeth

. My dentist is a friend and I asked him to seal all of my teeth prior to getting radiation. I brush gently for very long periods (sometimes 5 to 10 minutes) and have had NO problems post radiation. I do use Biotene mouthwash before bed and that seems to help
P.S. It might seem like I don't have faith in my doctors or treatment. That is not the case! The fact that I am still here is proof of their expertise. I thank them regularly for what they have done. My comments are in the area of quality of life and anything you can do to enhance good quality of life post treatment is worth doing.)