Aiming animation of a tower

Hello everyone,

in blender i have created a cannon. Now i want to aim on a target and i don’t know how to do this in the right way.
My first try was to rotate the whole Spatial (the cannon) but so you can’t tilt the tube of the cannon.
Then i created a skeleton for the mesh. In jmonkey i manually manipulate the rotation of the bones.
Ok now the cannon rotate and tilt to the target but when i move the cannon, the skeleton is still on the same position. This is bad because the angles of the skeleton are not the same of the cannon, so the aiming is wrong.

Is it possible to move a spatial and the skeleton automatically moves with it?
Is there a setting to move/rotate the child bones of a bone if i move/rotate it?

I wonder whether i should create 3 separate meshes. In jmonkey put the meshes together and animate these without bones.

Should i do this kind of animation with bones?

This is the cannon with the bones.