Furnace minecarts should be affected by hoppers and activator rails

The furnace minecart is one of the most useless features in the game, and there have been countless suggestions on how to improve them. These often include adding the ability to link minecarts to them, making them more powerful, and adding the ability to store fuel like a conventional furnace. While both would improve their utility, I think there needs to be two more features to make them interesting. One, they should be able to be refilled using hoppers on the side of the tracks, like furnaces. Two, they should respond to activator rails, with an off rail stopping them and an on rail starting them (in the direction that places it in front of any linked carts). That way, you can add some automation to them, as well as give it some features that powered rails can't do (especially if linking carts requires a furnace minecart). The only drawback I'd add is to keep them slower, so if the default max minecart speed is increased furnace minecarts still stay at 8-10 blocks per second.