1: Camping stores sell it. I believe you can get it from amazon.com too
2: Plants, that's an awesome question. There are various bromeliads, most of which are small kinds of Neoregelia. I use Aechmea gamosepala (spelling?). Of the other plants, there are Fittonia (the leaves with the white markings), Ficus pumila, and various aroids including Pothos. I have also added Dischidia "Million Hearts" to the terrariums since the last photo. Most of my plants, with the exception of Pothos and Dischidia, came from other hobbyists or Black Jungle. I have also started buying bromeliads from Michael's Bromeliads in Florida (they have a web site). Pothos and Dischidia came from Home Depot or Walmart.
3: The Ghost wood holds up for a very long time. Mine shows no signs of degradation after a year.