1. You have to buy the upgrade from Dell. The upgrade should be quite easy to install, just remember that like any other ROM-upgrade, everything on your PPC will be erased, so sync/backup before you start.
2. In PPC2003 there is supposed to be a buildt in function that scans for any available network, haven't tried it yet though (have ordered the upgrade, expected delivery 20. july
One thing to remember before upgrading though, you need new drivers for all hardware you may have (espesially WLAN/LAN-cards).