about 1 1/4 of an inch up.
Where it hurts them the least.
depends on the size of the vase or whatever you are putting them in, etc
one thing i DO know is that you cut them diagonally, so they can get the most amount of water ******* up in the stem =)
always start cutting at the bottom but cut it slanting the cut..and each day you cut a little more off but a slanted cut.
it depends on how long you want the bouquet, or how big your vase is
cut flowers in a garden or flower shope
to the length you want them at a 40% angle slantered to **** the water in better
good luck