maybe this will help http://polycount.com/discussion/188120/unreal-engine-4-lighting-course https://docs.unrealengine.com/en-us/Engine/Rendering/Overviewgood luck!
Are you exporting tangents or generating them in engine? Try both options https://docs.unrealengine.com/latest/INT/Engine/Content/FBX/ImportOptions/index.html
You want to do this in Engine. See about editing the physics bodies. https://docs.unrealengine.com/latest/INT/Engine/Physics/PhysicsBodies/Reference/index.html
you kind of can't but also kind of can the main texture is just a simple color for the outline it looks like they're using a duplicate of the mesh where it has been expanded, has flipped normals and a flat black material. if you google for toon rendering you should find some nice examples. Which engine are you planning to…