Oh, fun!
I just participated in a 35 mile ride this past Saturday - Tour de Rock in Little Rock. This was the first time I had been on the bike all season. Needless to say, I was a little sore afterwards.
You'll do just fine. I'm no expert but this is what I would do....
Having someone to ride with is always a good idea. If not, do you have a bike computer to help you determine what mile you are at? If so, I'd study the map and get a good feel as to where the rest stops (at what mileage) and where the major turns are. If not, study the map anyway to get a feel for the route. More than likely, there will be people riding close by that you can follow, especially at the beginning.
Most of the events that I've participated in have had signs at turns. Some were very small and hard to read, some were just writing in the road, clearly marked.
This sounds like a good event. I'm sure you'll have a lot of fun. Honestly, I enjoy these events more than running/walking events. They are generally more relaxed. One of the events I participated in last year was a blast! The rest stops were all themed stops and were more like big parties than a true rest stop.
I can't wait to hear about your ride! Have fun!