Two basic (probably n00b) questions that I can't seem to find answers to... 1. Is the GXM 40 USB "puck" just for XM/Sirius radio reception? I'm pretty sure I don't need it installed if I don't plan on using those services right now. 2. Should I run the leads directly to the battery (with proper connections crimped on of course)? Or is there a "switched" option? I read somewhere that the Garmins pull a small .25amps even while off. Is that small pull remedied by undocking the head unit? Seems like a "switched" option would be ideal, but not sure where to go from here. Thanks ADV.