linux kernel and fedora add-ons
 

I haven't quite understood. For example there are the bluetooth services; are these -implemented (at least for fedora distro, but also in general) inside the default linux kernel as modules,
-are they fedora add-ons inside the kernel, or
-or linux kernel default modules, which have however been improved by fedora developers?

Another example is the Redhat GFS support; will these be implemented as part of the Fedora-flavoured kernel or as a totally independent application/daemon/program,etc?

I try to understand the general layout of this os.
Thanks