For maps http://www.adventurecycling.org. You'll be roughly following their Northern Tier route. Maps show campgrounds, lodging, areas with stores and bike shops.
100 miles a day is doable if you're in good shape, but if you run into a few days of weather and headwinds it could be very tough.
You'll lose weight on the trip with that mileage, I lost 15 pounds on my cross country.
I'll leave the rest to others.
Regards,
Lee