1. You will not get a flat battery. The CANBUS will monitor battery level and switch off the port if the battery becomes critical to enable you to still start the bike
2. The reason it stays on is because the CANABS checks the port to see if it draws power 30 seconds after you switch off the bike. If power draw is detected the port will stay powered for another pre-determined amount of time. If you unplug your port after you switch off the bike and CANBUS detects there is no power draw you will notice it will turn off the port after about 30-45 seconds and even if you plug in a device after it turns the port off the port will stay unpowered
3. You should get a proper power system that goes directly to the battery and uses a switched source to power devices only when the bike is running. Something like this will work well as an example. this leaves your port free for phones and other non-permanent connections and allows you to setup alternative ports for heated gear, powering other devices
http://www.nippynormans.com/product...ntech-ap-2-auxiliary-power-fuse-panel-cen-af2
Or
http://www.nippynormans.com/product.../item/fuzeblock-switchable-fuse-panel-fuz-fz1
Example of how I did additional ports in the rear