Of course, before disassembling anything, I unplugged and turned off the gas supply.
To replace the spark electrode, I removed the drip pan/surface to gain access to the burner assemblies. Next, I unscrewed (with a 1/2" open-end wrench, I think) and disconnected the gas supply tubing from the burner assembly with the cracked electrode, and then unscrewed the assembly itself from the base surface. With the assembly detached, I flipped it over and removed the screw that secured the cracked electrode. I replaced the electrode with the new one, attached the wire from the old one to the new one, then reassembled everything.
To replace the ignition switches, I removed the control knobs, the bezel plates behind the knobs, and then the front panel surface. The bottom side of the front panel may be secured with a product descriptive label, which may need to be carefully cut with a box cutter along the seam/edge of the panel. And in retrospect, the bezel plates may not actually need to be removed, although removing them makes it easier to clean the panel and plates while everything is disassembled. With the front panel removed, I carefully pulled each ignition switch off its valve stem, and disconnected the harness' two power wires. I lined up each switch of the new harness to its corresponding valve stem, adjusted the rotation of each valve stem as necessary to line-up correctly with the switch, then pushed each one onto its stem until it snapped into place. I tucked the harness' wires neatly, connected the power, then reattached the front panel, bezels, and knobs.
Before I could install a few of the grate pads, I had to dig what was left of the old, obliterated pads out of their holes with the end of a paper clip wire.