Modules missing from stock kernel config

["Max Z." <wizardmax@xxxxxxx>]

I am trying to understand something. I opened up the .config file for the
kernel included with RH9 kernel source. Some of the modules that I know are
running (such as FireWire) are not selected. How are thise modules running?
Where they added independently of the kernel? What would happen if I will
recompile the kernel? And include the module in the kernel?

Thank You
Max