Q: Is the course really exposed to wind?
Q: Any sketchy descents to worry about?
A: Maybe, depends on your definition of sketchy. To error on the safe side I would say yes. Take a look at the elevation profile here to get an idea of where the fast descents are: http://www.almanzo100.bike/almanzo-100.html
Q: Are 1.95s overkill?
A: Maybe. Tires are a personal choice. If that's what you have on your bike stick with them. No need to 2nd guess this 5 days before the event. I've seen people ride the Almanzo course on everything from 23mm road tires to 5" fat tires.
Q: Is the gravel well maintained or a sand pit?
A: Gravel roads exist because cities/towns/counties don't want to maintain asphalt/ concrete roads. Over the course of the route you will see many different gravel surfaces: hardpack, chunky, loose, and sand. If you mix in rain add mud/ peanut butter to that list!
Q: Is the course marked at all or do I really need to pay attention to where I'm going?
A: Not marked. You are responsible for yourself. With that said, there are a lot of people riding in the event so your chances of always seeing someone on the horizon are good. But don't blindly follow a rider ahead of you. They might be spacing out and miss a turn.