LOL! Great post!
Here are a couple of tips for the climbing sections to keep you from spinning away:
1. Use your arms. No, I don't mean to pedal with your arms but, when you're climbing a steep pitch, pull back on the handlebars during the power portion of your pedal-stroke (like you're rowing a boat) and drive the rear tire into the ground. This helps add some traction to your ride.
2. Make sure you're drivind down on the back wheel without dropping your center of gravity too far back as this will cause you to "dolphin" (i.e. your front wheel will come off the ground). On very steep climbs, I always get my butt as far to the front of my saddle as possible (without becoming less...shall we say..."masculine" by having the front of the saddle poke me in the...
) and lean forward a bit. This keeps some weight over the front tire while simultaneously maintaining tractions.
3. Gear down before you get to the climb. On my roadie, I can generally make shifts anywhere I want while on my MTB it just isn't possible. When in doubt, go granny; you can always "gear up" when you get on the climb.
As for the descents; I'm solid on those too but we have quite a few "shuttle monkeys" on these boards who can probably be a bit more detailed in their explanation that can I.
Good luck and stick with the dirt; you'll learn to love it!