The multifunction switch can account for the brakes and turn signals. On 89's they go bad because the driving lights aren't on a relay. The full current going to both headlights and both driving lights goes through the switch, which gets hot, begins to melt/warp, and eventually things stop working well.
If you wiggle the wiper/turn stalk does it wobble around a lot? If so, get a new switch and consider putting relays on the headlights/driving lights.
You can also get some carbon buildup on the contacts, both there and on the master window switch. Do the individual window switches work their windows well? The window switch can be pulled apart and the carbon arcing can be cleaned off with a pencil eraser. Spread some tuner **** (dielectric grease) on the contacts before reassembling to help keep them clean.
As for the black button under the ignition, that's the key release button. You should have to push it to get the key to turn back to OFF from RUN. If not, your lock cylinder might be getting a bit sloppy.
