Welcome, Diane -- sorry you are joining our little club, but glad you chose to share your journey with us.
David, David and Christine all gave some good advice. Do eat as much as you can ahead of time. Also, keep in mind that everyone is different in the experiences they have during treatment. As you read through the posts here, you will find folks that sailed through treatment with relatively few side effects, and others who had a much more rigorous course.
I did not have a port, so had a new IV every weekday for 8 weeks. Upon review, I might have opted for a port if I had it to do over. I did not have a PEG tube. I ate lots of soup, mashed potatoes, gravy, etc. Lost about 30 pounds, all of which have miraculously reappeared now.
You need to drink lots of water, and rinse mouth with water, salt and baking soda solution (1/2 teaspoon salt and 2 teaspoons baking soda to a quart of water) several times per day. I also endorse the Biotene products.
Also, stay active and stay positive. May or may not impact your treatment course physically, but will definitely help you mentally. I agree that this is a BIG part of the battle.
Good luck, and stay close. Ask lots of questions, but remember that every case is unique.