Not really too sure but, ill take a stab!
you've flushed the coolant--- what is the current level on the clear yellow tank? make sure the coolant is half inch above the max line..Is the coolant light on?
valve cover gasket--was the oil on the plug itself? if the oil was on the internal side of the engine then the head cover or piston rings have an issue-not valve cover.
Ac filter is the cabin filter, and it would smell funky when the air is on if it needed to be replaced.
We need the CEL code. when the cel flashes on/off then you have a misfire and a fouled plug, might cause this. get the code scanned and report back to CEG.
Air bag on when you turn the car on is normal. if there was a problem it would always stay on. so this is OK is it only stays on for several seconds on startup.
for the wiring harness recall. call ford customer service, give them your vin and they should be able to let you know.
hope this helps a little.
