Controlling modules, and printing ing info during boot/shutd

Is the /etc/init.d/ the place to look around for the scripts that run during boot and
shutdown??

I need to print something when it shuts down to prevent the user
from turning the power key before linux is done as it makes the hd unclean.

I need to control the boot and shutdown more but I cannot find the info on
the debian site. Any ideas where I can get more info regarding the boot process as
I use linux to control a bending mashine running my program in Xsession and I think my
solution is far from perfect.