Going to your local hobby shop is something you should stay away from. As you learn, you will crash and the HBFP is about as easy a heli to learn to fix as there is out there. YOU need to learn to work on your own heli so you know what makes it tick.
The battery should be able to slide forward and back on the guide rails. You can do this by moving the little pieces of clear rubber tubing as needed. This will allow the battery holders to move until you get the center of gravity (CG) where you need it. When you go to Lipo batteries, you will need to move the battery forward because they don't weigh as much. The NiMH batteries are quite heavy and require more power just to lift their weight.