You may also want to check out jmetest.intersection.TestPick as it shows both picking and how to check for target being hit by weapon.
How to make movement from image? Well usually in the 3d world most movement is done by models of sorts. You load model, move it, and the user sees the animation. If you really need to animate an image, then there are a few options, none very good as far as I know. You should probably check out this thread: JFjr - the JMF/FOBS/jME video renderer
Basically I just suggest start out with something small, some simple tests… and go from there.
To me it sounds like you may need a 2d engine, jocko. If that's the case, you should look for another engine, making jME handle 2d as you want it will require a lot more work and learning than if you'd do it with java's builtin 2d and sound capabilities!