config files and packages

[Jeff Cours <jtc@alumni.rice.edu>]

Apologies in advance for a very much newbie question. I'm trying to 
make the transition from Mandrake to Debian (stable right now, with 
plans to track testing once I get stable working). There are a bunch 
of things that Mandrake auto-configured that I'm going to have to 
configure manually with Debian. I figure I can take care of most of 
them by comparing configurations between the two distros and porting 
over the stuff I need.

My question is a little more basic, though. I still don't completely 
understand Debian package management, especially the way it handles 
config files during upgrades. Can I just edit files under /etc as 
necessary? What happens to them when I upgrade - are the upgrade 
scripts smart about keeping my changes, or do I need to tell the 
package manager about them explicitly? If it's as simple as the 
package manager not touching anything under /etc that I've modified, 
what happens down the line when an application changes its config file 
format?

thanks in advance,
Jeff Cours