Firstly congratulations on your 10th anniversary aspiring Knight @ediblehedge! Reading your OP makes me think, you must be a veteran in all things suffering and what a wonderful (painful) way to celebrate the anniversary 
#itwillallbefine
Sir Glen has put it rightly so, the warm up and cool down sections are the best time to fuel the fire 
On the chamois cream, I can concur with both Sir Glen and Sir James that it is best to invest in it and be sure you have your undercarriage get used to such a thing (if you haven’t used chamois cream before) for the big day.
Personally, I used 2 kinds, one which is called ‘snow-flake cream’ and the other is just the regular Sudocrem.
When it comes cycling wear, you seem to have a good amount of kits there. I changed kits every 3 rides for first half and every 2 rides towards the second half of things.
Food wise, I think what you have planned out if good. Just so, it works best for you and your GI system. It’s a very personal choice, so eat what you like and and what works best for you.
Btw, I have made a short write up about my experience from idea conception to the actual questing day itself. You can check it out here. 