The answer to the transcript question is yes; after every chat they post the transcript on the LPUMB.
All the wallpapers, buddy icons and screensavers are exclusive to each year, however the ones from LPU3 and LPU4 are on the Enhanced CD's.
The remix2win contests were held by Verizon Wireless. They made a website called http://lpconcerts.com where fans could create their own remixes/mash-ups of songs by artists from Projekt Revolution, though the second competition only featured Linkin Park songs. The contests have since ended, but the website is still up and running.
Projekt Revolution 2002 featured DJ battles as part of the show. A couple of vinyls used in the battles were sold on eBay. LPL hosts a rip if you're interested.