First off, did you correctly calibrate the battery when you purchased your PB? Calibrate = Fully charge, run down until warning message appears then recharge.
Swapping out the battery is easy - I always carry one in my backpack as I'm on the road often. Flip your laptop over - you'll see 2 slider thingies (the technical term escapes me) you slide those (exposing the color orange under the sliders. Once those move the battery pops up. That's it.
As far as recharging spare batteries no company as of yet has an external charger so you will have to charge it in your AL PB. For best battery life be sure to calibrate it. You only need to calibrate the battery once. You may also want to open energy saver and adjust your battery consumption settings.
I second your hope for fuel cells.