Weapon Aim and animations

Hi! I am completely new in regards to animation.
I am trying to create a first person view using a full body mesh, and trying to decide whether to continue this way
Basically I attach the camera to a socket in the head mesh.

It works relatively well, but Im worry about aiming and how make it work with various types of weapons (which will have different sizes and heights).

-Can I use the same animation for the precise aiming and the position for the hands?
-what techniques should I use? (IK etc)
-Is rig on weapons necessary for these techniques?
-More important … where I can find more information?

Thanks and im sorry for my English!