There should not be any stamps on a criket filed - whatever that is!
20.13 meter
one. number of stamps is determined by weight, not distance
A roll of stamps is exactly what it sounds like. It is a strip of stamps, usually 50 to 100 stamps, could be as many as 500. They are 'coil' stamps, which means they have two straight edges and perforations between the stamps.
Stamps depend on weight, not distance. You can find much more here: http://www.usps.com
Postage is based on weight, not distance.
Stamps are not based on distance, but rather on weight. Therefor, 1 stamp should be plenty of postage for a standard letter.
The value of the Apollo 8 stamps depend on condition and if they are singles or in sheets. Sheets of these stamps in mint condition are valued between 15.00 and 18.00 as of 2014.
You best method would be to use the stamp mount manufacturers measurements. Most provide a template that will allow you to match up your stamps with the proper size of mount and this is the most accurate way of getting the right size.
Gutter
Yes, other than the oddities, the coil line number stamps have value.
distance is irrelevant...number of stamps to use is based on the weight of the envelope....if it's more than six or seven sheets, add anoter stamp
Three stamps ($1.26) are needed because it costs between $0.98 and $1.18 to send a letter to Korea from the U.S.