Jim, glad you finally have the surgery set up. Now just take care of yourself before this!!! Slow down and get rest, bulk up as much as you are able to. Drink ensure or Carnation VHC to put some weight on and increase your protein intake to help you heal better.
One of my pals here sugested a hi protein powder that I add to my feeding formula. It can also be mixed with any type of liquid, it dissolves easily and has 25 grams of protein per scoop. I get it thru the OCF Amazon link. Its something worth a try.
http://www.amazon.com/gp/product/B000GE0D8O/ref=oss_productWhen you have the pre admission testing, tell them about any mouth problems you have. Make sure you stress the fact that you are not a regular person and care must be taken with your mouth. They will use a breathing tube. If you have any throat issues, make sure you speak up during this testing.