I don't know much about how default.pl and player.pl work, so I didn't post earlier, but if you just want to know about how to use quest globals, it is really pretty simple. I use it a TON in my custom quests.
Here is one example that should help you understand it.
http://www.eqemulator.net/forums/showthread.php?t=25556
But, I have plenty of others if you need more.