5 of you will make a good draft when road conditions permit too. I got a great tow off a few guys out for a ride in Yorkshire, I asked to tag on the back, and before I knew it I was flying along at 20mph average! Even with panniers and all my kit. Of course you will swap round, but it does make a big difference getting a peloton going.
Food wise, for an average 10 hour day (80-90 miles) I'd have porridge for brekkie, mid morning snack of wholemeal pitta + babybell+ saucisson/chorizo, cafe lunch of soup/sandwich + cake, thenmid afternoon another pitta as before, then pub dinner in the evenings (with beer)
In between all that i always kept a selection of jelly babies/fuit and nut mix/oat cakes in the bar bag for nibbles. I also had 2 x 1 litre water bottles that I normally re-filled at the lunch stop.After nearly two weeks of that little lot I a) never ran out of energy through the day - complex carbs and protein are key, and b ) I still managed to loose nearly a stone! I was peddling a very heavy bike though, so your calorie intake might be slightly less.
I didn't use any sports nutrition products or gels, just ate fairly well and drank a pint of milk in the evening after finishing riding as a recovery drink.