(2) All the plant tinders I have used to date have been easily prepared by charring. Some tinders in the 18th century were prepared by soaking them in nitre, but Potassium Nitrate is not easily processed in a wilderness situation unless you use urine. Even so, charring is an easier preparation than urine and it works better.
(3) The tinderbox is used for storing and carrying tinder. It is used for making fire by striking the sparks directly into the tinderbox. It is used for preparing tinder by placing freshly charred tinder in the tinderbox and closing the lid to smother the smouldering tinder. Uncharred tinder material can be placed in the tinderbox with charred tinder, and it will get charred with use when making fire.
(4) Not all tinderboxes are waterproof. I recommend that you keep your tinderbox, a candle stub, and a little kindling in a greased leather fire bag. Make it large enough that the top/opening can be rolled down for closure.
(5) I recommend that you always carry spare tinder in a greased leather bag. I carry my spare tinder in one of my gunpowder bags.
My brass tinderbox and fire steel.
Tinderbox with charred plant material; bracket fungus and punk wood.
Tinderbox with both charred tinder material and uncharred tinder material.
My greased leather fire bag.
My greased leather gunpowder bag. I carry unprepared tinder material in this gunpowder bag. The residue from the gunpowder coats the tinder so it will catch a spark without having to char it.