1. Solar panel on the roof - it would only have to be small, A smartphone runs on milliamps and would be overpowered for this application.
2. They log the location on a periodic basis and upload the file at the next opportunity. If you go off-air for 3 weeks your file could be forwarded for review and the last know location taken into account. If you go off air in Central London for 3 weeks, you're probably stuck in a tunnel If it's the rural reaches of the South Oxford - well, who really cares? But you might get a visit....
3. A combined solar panel/antenna (something the size of an open paperback) on the roof, near a mushroom vent. Even smaller box (smartphone sized) on the end of a cable which would join the two. In the absence of a mushroom vent, a 4mm drill bit and cable glands may be required. In time, boatbuilders will come up with a more elegant solution.
4. Beat them with lengths of rubber hose, of course!
5. Not really - it would be easy to interrogate the data for any tags moving in close proximity, exceeding 4mph, or leaving the canal network. This would make it quite hard to move a tag around the system unless you're prepared to carry it while walking or cycling slowly. If two boats are moving breasted up, they'll be flagged but at least CART will have a location to program into their Predator drones for the pre-strike recce