Linking/Appending action and associated mesh/armatures, and camera issues

I’m just starting to learn blender, and I need help with a project I’m working on. Can anyone provide advice, or direct me to a tutorial relating to these issues:

I have a rigged mesh, with associated animations. I need to take that mesh and put into a another blend file, with the animations remaining intact. The mesh itself is a human figure, and the animations include walking, etc. In the mesh’s blend file, I’ve set up logic so that the mesh will move forward when ‘W’ is pressed, and the walking animation will play. I need this behavior to transfer to my other blend file when I link/append the mesh. Also, I’m not sure I understand the advantages/differences between linking and appending.

I need help setting up a third-person camera that follows an object, but is not bound to viewing one side of the object. Currently I have a box, which I can move with keyboard commands. The camera is parented to the box. If the box falls over, the camera tilts with it, and the resulting scene is very confusing. I need the camera to just follow the box, instead of being glued to it.