I think Sidi Dominators with SPDs are an ideal combination of comfort on the bike and street. I once flatted a mile or so from home and just ran the bike in with them.
About the SIR food/mechanical/control issues. Controls will sometimes be 50 or more miles apart. I use two 1 liter bottles. If it's an SIR control out in the middle of nowhere, an SIR person drove there. They probably have some minimal mechanical help, but don't count on it. They will have water, sodas, and sometimes food, all free. You paid a fee, right? If it's at a grocery store, well, no mechanical, but food for purchase. Sometimes there will be a middle of nowhere control just after a minimart or shopping center, and you'll have been expected to get food there, not at the control. Ask the organizer or someone who's done the route before for specifics of that route. The mystery thing is a big part of randonneuring. If I were you, I'd carry a good bit of your favorite stuff and then try to mostly eat out of stores, saving your stuff for when you get hungry on the bike, which you certainly will. I try to carry about half of the calories I expect to eat, but many people carry much less.
OK, one month before the first one. Time to get busy riding. I lead a Sunday ride for Cascade. Show up.