Oil filter will come off with bare hands if you're a tradesman. Otherwise, the "hammer a long, thin, flat blade screwdriver through it and turn" trick works.
The sump plug at the front is for manual cars; it's where the oil level (or is it temperature?) sensor goes.
First thing I suggest on the airbag warning light is to unplug the small yellow connectors under the seats, clean the terminals with either isopropyl alcohol or Servisol contact cleaner and plug/unplug several times before refitting.