Help? Desktop launchers

Greetings.

I'd like to add to the default set of desktop launchers on our systems, and
am new to gnome and how these are established for new users on their first
login. I do not by choice want to have to add these additional desktop
launchers downstream, after a user's gnome environment has already been
first established (although knowing how this would be done -- without that
user's intervention -- would be useful for pre-existing users, so let's
include this as well).

Any hints, observations and suggestions appreciated!

Questions:

How during a user's first session is the gnome environment set up -- what
starts the ball rolling? Who creates the various directories and files?

From where is the default set of desktop launchers defined? Is there a
system-wide template for these somewhere?

Last, in what rpms are these various things to be found (if source changes
would be required)?

Many thanks, this is going to seem a bit foreign to me for a while.

Jeff Bernhard                                   [email protected]