Lenny, I can add little to the good advice you have already received. Pay particular attention to what Tom says about the PEG. Water is vitally important, so one way or the other, stay hydrated.
With regard to the neck surgery, it is not a big deal -- really. Pretty much a piece of cake after what you have already been through. This will not be painful and will not set you back in your recovery from rad and chemo. By the second day after my neck dissection, I was off pain meds. Expect swelling, but that too goes away in a short time.
I had mets to lymph nodes, also around my juglar vein, and am 4 years out from diagnosis, feeling and doing everything I was before it all hit the fan.
Lenny, you are through the worst of it, and will see slow but steady progress in your return to full function. Keep us posted on your progress and feel free to ask any questions that arise.
Joanna