3) How can I listen to some tunes?
For many home users, once you get past word processing, the most important app is a music player. RealPlayer, famous for burrowing its way deep into Windows systems, is one of the few major players to offer a version for Linux. (It would hardly be fair to expect the same for programs named Windows Media Player and Winamp, though an open-source clone of the former is in the works.)
The Linux RealPlayer is based on the open-source Helix player, which offers downloads here. (However, since the Helix page also points to the Linux RealPlayer, it's easiest just to get that.) Another free player is amaroK from the KDE group.
Where to go to buy music is a tougher question. Neither iTunes, Yahoo Music, nor Urge run under Linux. As for Rhapsody, users can get a subset of the service (basically, online music playing) but you can't buy songs online and you can't install the full version of Rhapsody on a Linux box. Most vexing is that, without persistent searching, it's hard to figure out precisely which pieces of the service work and which don't. A Rhapsody customer service answer attempts to explain; so does this Newsforge article.
One of the few operations that is set up to run under Linux is MP3tunes.com, the 88-cent-per-song online music store set up by the aforementioned Michael Robertson. If you're into artists off the beaten path, another service, called Mindawn, may be for you. While Mindawn doesn't have much music you've heard of, it does eschew DRM and offers its downloads in the FLAC format favored by PC audiophiles in the know.
Folks who store MP3s on their PCs are also often in charge of the family's digital photos. For them, there's Google's Picasa image management and sharing software.