FM Style Template is a template for "Bitmap Style Designer" tool (Tools > Bitmap Style Designer).
For more information about Bitmap Style Designer, please, read documnentation:
FM Style Template not depends from FM style format and you can use templates since XE5 version -
just run Bitmap Style Designer from your current IDE,
open template and save it as FM style (*.style) with specific for this version style format.
Then you can use *.style files in TStyleBook component.
For more information, please, read documnentation:
Yes, you have full rights to edit, rename style template as you want.
To edit and test it, you must use Bitmap Style Designer tool.
For more information, please, read documentation:
Information about how to export / import images from style template:
See specific blog about that: