- It has a voltage sensor to preserve the battery. If the battery is low, it won't charge the camera.
- You can connect it to any (suitable) fuse in your car. Depending on your choice, it can have uninterrupted access to the battery, or it can require the ignition (as Padlock962 did).
- If I remember it correctly, parking mode is a separate function that you can turn it off. Check the manual. I don't know why you would install the camera and not use this function, so I didn't bother checking it.