Should we refill / replenish the gas cassettes, cooking condiments, fire-starters, or charge battery when we drop off the camper?

No, these are our gifts provided to you to maximize your experience!  You do not need to replenish the gas cassettes, cooking condiments (oil, salt, pepper etc) or charge the battery.
We only require the used kitchen/camping items & inside the camper to be cleaned, your rubbish to be disposed of and the overland camper to be refueled before drop-off.