First, congratulations on taking on the relay. You will have an absolute BLAST!
In the days leading up to your race, I would follow what Coach Nancy says regarding training this week. You will not lose any conditioning or endurance, and in fact will gain some by the extra rest. By race day you will be rarin' to go!
As far as what to eat this week, I always try to keep my diet as clean as possible. Nothing out of a can or box - whole foods only. Fresh fruits and veggies, steel cut oatmeal, fruit smoothies, pasta, whole grains (quinoa, brown sweet rice, barley, etc.), chicken breast / tenderloins, fresh fish (salmon, tuna), green tea, and a little more water than I normally drink. The night before the race, don't eat anything new or different, and make sure it's easy to digest. I usually go with angel hair pasta, 1-2 small baked chicken tenderloins, and veggies. Sometimes I buy the Green Giant Health Blends (in a box) and put that over the pasta. If I want a sauce, I'll either use a little Smart Balance spread or drizzle a little olive oil over it and sprinkle a little parmesan cheese on top.
During the race, you'll probably not want to eat much 1-2 hours before you run your leg. Eat what you normally eat before a run, and if you feel you need something within the hour before your leg, then have a gel or energy bar. Don't forget to take in some electrolytes immediately following your legs in order to keep your energy up for later in the race.
Good luck. You will do great!
"God gave you your body as a gift, so you should take care of it." - My Mom