Will all of your configuration remain the same after compiling the new kernel
 

Like XF86Config configuration, fonts.conf etc will remain the same after compiling the new kernel?

I just want to make sure about this before I try to do that exciting thing.

Thanks

They should do, the only config that should change is the one in boot for kernel itself. You may have to alter your modconf though.

You might want to edit rc.modules to stop trying to load anything that you compiled into the kernel that used to be a module.