I think it is more about 12in... but that could vary depending on type and I'm not sure how people measure it with folds...
As for fragging it's actually very easy... I have a thread about it awhile ago (I was nervous about to cut up my fisrt leather)
anyways you can just cut off a section and it will grow into a new one and the cut off peice will heal. Also you can just cut the entire crown off, a new one will grow from the stalk and you can chomp the crown into smaller sections.
you can check out
www.garf.org they have advice a fragging many types of coral