Unity links from Stephen Aldridge

Physics:
Physics overview page:
https://docs.unity3d.com/Documentation/Manual/Physics.html


This page contains some useful information, especially the chart at the bottom of the page.
http://docs.unity3d.com/Documentation/Components/class-MeshCollider.html

GUI Libraries:
NGUI:
http://www.tasharen.com/?page_id=140
UIToolkit:
http://forum.unity3d.com/threads/87917-Prime31-UIToolkit-Multi-Resolution-GUI-Solution-Ready-for-Use-and-it-s-free

Animating within Unity:
https://docs.unity3d.com/Documentation/Components/AnimationEditorGuide.html

Also, if you're trying to script imported animation clips then take a look at the ThirdPersonController.js script (mainly just the "ANIMATION sector" section). You can find it in Unity inside the Character Controller package.

Hope this helps!

--
Stephen Aldriedge