Just to add to what Henry said I would go for the play and charge kit, they are not much and it will save you in battries in the long run. all the play and charge kit is is a (very long) lead that connects the controler to the usb port on the Xbox so you can continue playing when the controller is charging.
if you want a decent shoot em up then call of duty is fantastic but I really would suggest getting the live service so you can play it online... it's great fun :)