In this paper, we discuss some recent progress toward addressing these questions. Observations with the Spitzer Space Telescope have shown that the amount of dust in debris disks decreases with time on average, but also indicate that dust production is stochastic. At least some debris disks contain small amounts of gas which has very different characteristics from gas in younger protoplanetary disks. The most complete inventory of gas in a debris disk to date unexpectedly showed that the gas is extremely carbon-rich. Finally, recent studies of the albedo of dust in debris disks have shown an extraordinary range of colors, including very red colors indicative of organic material.