OS X :: F12 Does Not Open DVD Tray?

my first question is: where can I get a quick start to "take control" of my brand new used G5 late '05 2.3 dual core Power Mac? I'm accustomed to going to device manager to check on things, update or disable drivers, partition, reformat, set selective start-up, you know; all that. I bookmarked something like Switch 101 and am left shy of the depths I wish to go.

I've fiddled with an acquaintance's MacBook Pro and found it somewhat intuitive, so navigation in and around the apps won't be too difficult to switch over to but how can I do something like pick and choose what I want to show up in my task bar or whatever the Macquivalent is.

And secondly, F12 opens the Dashboard not the DVD tray. Option F12 doesn't help. Unless I need to literally "hold F12 until the open tray appears..." or something like that. That hasn't worked either.
I'm sure I won't regret the switch. I've been threatening to for the last three or four years; five of which is my level of PC-ing.