Hi Lee, a few remarks about your questions. Most people recommend starting as you mean to go on-i.e. don't go faster than you feel comfortable with, as you will burn out, and don't get unwittingly dragged along by faster people, particularly in the excitement of the first couple of hours or so. Remember the strategy of walking from CP to CP, and not getting daunted by the idea that you still have 80 miles to go! I change my socks about every 15 miles or so [does increase the weight, but I live with this] & have extra pairs in breakfast bag in case it is very wet. I have changed them more often sometimes. I try to remember to moisturise with every sock change (Palmer's cocoa butter or similar). This is personal tactics and others will have different ideas.
Sleeping: I have been known to lie down in a field for 15 minutes, and once spent half an hour asleep at breakfast, but as I am very slow there is really no time for much more. It is surprising that in the second night, you don't feel twice as tired, for some reason-the field episode was in the afternoon of day one, when it was also hot. We usually have a plan of sorts for the event which allows different amounts of time at CPs-e.g. much longer at breakfast, and then towards the end when feet are dragging. Again this is personal-some people just whistle through everywhere! The plan looks at how fast we expect to go at each stage (i.e. a reducing average as the event wears on, and overnight when it is less easy to sustain faster speeds), and 'predicts' what time we will arrive at CPs. This can be useful to keep a check on how you are doing re closing times. It is also really nice to have time to chat to the CP marshals.
If it will help you to look at a plan, just say and we will get an old one to you.
Re food: don't carry too much (I always do, in spite of this advice!), but do carry something you really really like and which will give you a lift. 100s normally are very well catered, so you don't need to carry a lot-but if you find you can't eat CP food at some point, then a little snack of your own along the way might help & it can be a great morale booster. I carry chocolate, chocolate raisins or cranberries, dried fruit, perhaps a few high calorie bars. Put a few extras in your breakfast bag.Think about including electrolyte tablets.
Sorry for going on-you have focused my mind, as I am entered into the NY 100: I haven't done the last 4 for various reasons and haven't finished one since 2009, so I am hoping this one will break the spell! As you are discovering,there is also great camaraderie on all challenge walks, especially on the 100, so you will surely be able to walk with others and get/offer support.
Finally, don't think you have to keep doing long distances right up to the event. Just keep walking and stretching! Good luck.