Frank, first of all it's very admirable to see that people are still willing to take music even at your age. Now onto your questions:
1) The thing with the metronome is often used for beginners, since as you probably noticed after playing again after using the metronome, your hands are a lot more synchronized than before. However, when you refer to "standard," there are many different methods of practice people use. I believe that when you get to a higher level of piano playing you should have enough experience to be self-concious about your own rhythms and eveness, although it would do no harm to use your metronome once in a while, I mean you didn't spend those 50 bucks for nothing, eh?

Concerning slow practice, it is one of the painful things why many young children quit the piano, is due to boredom. Perhaps with easy pieces slow practice doesn't make much important, but Frank if you listen to some more advance pieces (perhaps you could download Chopin's polonaise on kazaa or winmx, etc.) the rhythm and beat are all very fast and many, many notes and chords run at the same time. So if slow practice wasn't used normally, it would be almost impossible for normal people to get better at the piece. As some other user here used as a quote from some famous pianist, "Practice 50% slower 75% of the time."

2) Your timing schedule sounds fairly reasonable to me. Just keep in mind, you're learning how to play piano because of your enjoyment for this wonderful instrument (i hope that's the picture), so just try to make things more enjoyable for yourself as long as you're keeping up with what your teacher wants.