Hello and Welcome to AMD forums,
1. Should you mess up the default drivers?
If your new PC comes with pre-installed operting system and drivers, then don't rush updating the drivers and software. Insted take your time to enjoy it. Usually people update drivers a) to fix issues and/or b) get better performance.
If this is a self built PC then after you install the operating system you'll need drivers. For a newbie I would recommend those that come on cd/dvd with the hardware, but you can also get their latest version here,
Graphics Drivers and Software
2. Can anyone point me to a good detailed guide on AMD Catalyst video options that explains what each option does?
a) AMD Catalyst has pretty good built-in help files that you can search to quickly find answers
b) AMD Catalyst User Guide PDF