I can't answer because I have other question open, sorry, but here I send any comments and clues to solve (I hope).
For the FUSE PANEL, location and description, I suggest check the 2000-Pontiac-Grand-Prix-Owners-Manual
(page 330 and next). A/C have one "diode". Check it.
About your radio display, sound like a internal problem, keep in mind that the CD is working.
The Security Litgh, its possible that you have any problem with the THEFT system or any aftermark alarm (if you have).
Resetting Oil Service Indicator Lights -
Center If Equipped). Turn the ignition to ON without starting the
engine. Fully press and release the accelerator pedal three times
within five seconds. If the CHANGE OIL Soon indicator flashes two
times, the system is resetting. Turn the ignition key to OFF, then
start the vehicle.
If the CHANGE OIL
SOON indicator comes on and stays on, repeat the procedure. To reset
the OIL LIFE indictor if equipped with a Trip Computer: Press the
trip MODE button until the light appears next to OIL LIFE. Press and
hold the trip RESET button until the oil life percentage changes to
be 99 percent.
Hope helps (remember rated this).