In looking at the pictures posted on the website, I don't see that people have cue sheets. The route is more than likely marked with "Dan Henrys." In my experience, most organized rides like this are marked like that. So, while you'll likely get some form of a cue sheet or map, you can follow the markings instead.
As for lunch, I've seen it both ways so it's hard to say. Most organized centuries offer enough food and enough "real food" along the way, even if there's no formal "lunch." You're much better off, in my opinion, eating small, frequent meals anyway, than a full-on lunch. In any event, if you want to stop for fast food (I'd rather go inside that go through a drive through surrounded by car exhaust), by all means do so. Or just pack a PB&J for a healthier alternative. From my experience with organized rides, there's no point in bringing along a ton of your own food unless you're a picky eater. The SAG stops along the way are usually more than adequate.
As for how crowded, I don't know. Why don't you call the bike shop that sponsors the ride and ask them your questions? Even on crowded rides, people tend to get spread out, but I doubt that you get lost or left behind. You're riding with your DH and a friend, right? They'll have SAG wagons if nothing else.
You'll be fine. Seriously. Have fun. Tell yourself that you can do it and, I'm willing to put money on this, you will.
Live with intention. Walk to the edge. Listen hard. Practice wellness. Play with abandon. Laugh. Choose with no regret. Continue to learn. Appreciate your friends. Do what you love. Live as if this is all there is.
--Mary Anne Radmacher