Personally I would go for a light spin on Friday. One's legs often feel a bit dead after a day off the bike. Don't worry about riding more today and tomorrow. The usual advice for the days before a big ride/race is to cut back on volume but maintain intensity.

As for nutrition, I'd suggest you take some food with you that you know agrees with you when riding. The food provided at the stops may be absolutely fine, but it may not appeal, and it has been known for food to run out. And while energy chews may be helpful, I'd suggest that something more sustaining might be good to have. I'm eccentric - if I'm going to be out for a long time I tend to take a cheese sandwich. Dried fruit, especially figs, are also on my menu. Your choices will be different, but you get the idea.

Have a look in the long distance forum. There's a stuck thread entitled "Tips for riding a century".