In addition to the rectangles of various colors you will see on trees and rocks, you will also see posts at intersections of trails, indicating which way to go. The metal bands on the posts will indicate trails, directions, and distance to landmarks. Be sure to look at all sides of the post to make sure you don't miss anything.
Midweek in October is very fine for the magnificent colors. I have heard that 100000 people climb Mt Monadanock in southern New Hampshire every year and 80000 of those climb on the weekend falling in the middle of October. I would not be surprised if similar numbers occur here along the Skyline Drive. Go in midweek if you can to avoid the traffic.
Skyland Drive is the scenic road that goes through the entire park. Tourists go either very slow(for sight seeing) or very fast on the this road. Use caution!