Here are some answers to your questions. I hope they help you!

Here are my basic questions:
1. I'd like more information from people who have had the neck dissection - it doesn't sound quite as easy a recovery as she indicated.

It depends what type of neck dissection they are talking about. If it is partial, you should be out of the hospital within a week with a little swelling and pain that can be managed with some drugs at home. If it is radical, then it is a bit more involved with the muscle, so it will take longer to heal. I had the partial, so that is the one that I am the most familiar with. My neck was stiff, but massaging it greatly helped and now their is barely any scar.

2. Is it reasonable that she isn't involving an oncologist at this point? She said unless any lymph nodes come back, we won't need to. Is that reasonable - to not do anything precautionary. (I'll be thrilled if that's the way it goes!)

I went to a cancer center from the beginning, so my experience is different than yours, but for what it is worth, I feel that it is important for you to be at something a little bit more comprehensive. Even at a cancer center, if there is no nodal involvement, you will not meet with the radiation doctor or oncologist if that is the recommendation. However, I found that if there is nodal involvement, you already have a team that knows how to work together and the transition from surgery to radiation and oncology is pretty smooth. Sometimes dealing with people at multiple locations can be more of a hassle than you want to deal with at this point. At least it was for me.

3. Am I crazy if I don't get a 2nd opinion between the PET scan and the surgery? I'm in Central California, so could go to one of the major university hospitals if I should do that.
I'm especially thinking that if the PET scan does show something else, I should get some more opinions about treatment - but don't want to wait very long to get the thing removed from my tongue!

I never got a second opinion, but I was also at a major university hospital from the beginning and I was 110% comfortable with what they were telling me. If you are feeling the need to ask this question, it might not be a bad idea to get a second opinion if you can.

I too had the same diagnosis as you. I had a 1.2cm tumor on the side of my tongue (non smoker / non drinker and 4mm one in one node that did not show up on the PET (they don't that small). Mine was well to moderately differentiated. I had the partial glossectomy and a partial neck dissection.