Confused About Animation...

Hi, I’m currently very confused about animations for a 3D fps/adventure game I’m trying to make.
Should I have the player’s body be just hands or an actual, full body? Should I use the bones (not sure what exactly it’s called) to do the animations in Blender and then import them into unity? Or should I do the animations in Unity itself. Also, if I have some bots in the game, and I want them to use the same weapons as me, do I need to animate each weapon for every one of them? Or is there a simpler way? Finally, say I want to switch weapons on my player character. How would I do this? Would I use IK or something and then use the bones of the character? I’m just really confused as it stands, so any clarity into animation would really help; I like designing environments and coding a lot so I’ve never paid any attention to it. Thanks!

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