" How much do I use? "
Normally about one square inch is enough: in the Featherstick photos, I have used a strip about 2" long and ½" wide. Practice striking sparks onto small pieces, you will soon learn how much you need. The drier your tinder, the less charcloth you will need.

" Can I use the broken bits? "
Certainly, just push them into the centre of your tinder "grapefruit" and strike a spark.

" Can I pay cash? "
Of course, at your own risk: sellotape the coins to a piece of cardboard though, to prevent theft. And don't forget to include your name and address.