The first question is easy: you can precompose the solid & Logo layers to make a single layer.
But the second question is a little unclear. If I read it properly, you want an Indiana Jones-style line of travel to follow a 3D camera as it travels across a map. But if the line is FOLLOWING the camera, how would the camera see it? Puzzling.
I do my Indiana Jones, "route is drawn on a map" trick in the following way:
1) Get a great, big map layer, much bigger than the ultimate comp.
2) Using the pen tool, draw an open-ended mask (aka a path) on the map layer to delineate the route
3) Add the Stroke effect to the map layer to animate the route.
4) Animate the map layer's anchor point to follow the route as it draws on.
It's all done in 2D, no camera necessary.
The camera is leading your arrows form your previous post?
Learn how to use nulls.
Parent the camera AND the layer to the null. Offset the camera above and in front of the null. Everything follows the null's path. It's easy.