1) All mediator jumpers closed for a 4T with Radeon.
2) The Picasso install can be done any time once the Mediator Installer is there.
3) I'm guessing the graphics go to hell due to out of date Setpatch or drivers.
4) The Mediator files can go in anywhere before configuring the P96.
5) I usually do: OS3.1, IDEFix97, reboot, OS3.9, Mediator, P96, then BB 1, 2 - reboot -- BB3, and most recent 4, reboot.
6) If your FastATA card is working you can install to it or use the T's IDE then move the drive. It shouldn't matter where.