In reply to Lee Sargeant:
Hi Lee,
A couple of thoughts after filling it in (though it's probably too late to change much)
You ask for backpack size (small, medium, large) but different people will have different ideas of size. It might be good to ask for size in litres. Also, if you're thinking about what people are willing to carry, weight might matter more than size.
You also ask where I would carry medical equipment. I said backpack, as that's the default place for everything, but the other options you list might work if it was something I needed regularly or potentially in a hurry. In that case, strapped to the chest (using rucksack straps) would be the most likely option.