no one has really answered you fully
no1: fuses, fuses and fuses.
my gadget friends blew my fuses by plugging in the 300W invertor into the clearly marked 150W only socket in the front.
then they plugged it into the cigarette lighter.
those two fuses were hard to find, but they were on the LH side kick panel. I am r/h drive here, but i am assuming they'd be either there, or on the other side. And these ones, both r'h and l/h side are smaller than the ones in the big fuse box under the bonnet / hood.
So you need to buy both types of fuses. And a lot of them.
To see the ones inside the car, you'll need to get up with a torch/flashlight .....you'll see where it is....took me ages.....the back of your head on the carpet, your eyes looking up and to the side (depends which side of the car) but towards the kickpanels........remove the kick panel...the fuse box is more towards the front of the car than you would think.
No2: Fire extinguisher.
Know where you are going. "Normal" ones should be ok. But yu might need fuel specific / environmetnal specific types. Here in Oz we have this grass called spinifex......apparently it's hard to put out and you need a specific type....
4WDing, Camping & Caravanning around Australia @ ExplorOz Forums might help there.
No3: tyres/tires...depends where you're going
No4: water. water. water. Canned/tinned food. Depends where you are going.
No5: Warm clothes / sleeping bags. ditto.
No6: WD40, CRC, etc.
No7: A quality socket set, spanner set. You dont need a full blown deisel mechanics toolkit!!
No8: fan belts...other belts. You have a name...aah serpentine belts...Pantyhose has been used in outback Oz in emergencies! yes really.
That will do me for now
cheers
peter