You can mount one where you like, its just a case of hiding the wiring. http://www.ebay.co.uk/itm/12v-Water...329992?hash=item4d349f31c8:g:FcEAAOSwy4hURiSr
Pretty much yes. I plug mine into the Optimate socket on the bike. Lets me run a phone charger lead into a tank bag if I'm on a long run or using it for satnav.