Does the BIOS update offer anything that you need ?? (ie. is your CPU a new CPU that the old BIOS does not detect properly, does it fix any other issues, etc.) - read through the BIOS update notes to see why it was updated -- If not then NO you do not need to flash the BIOS (and as you mentioned if done wrong it could turn the MOBO into an expensive paper weight - so if not needed best to not do it if you are unsure of the process)
As for the CD it contains the chipset drivers but they are usually a bit out dated by the time you buy the MOBO so best to download the latest version from ASUS and use it instead. Same goes for the video card and it's included CD.
If you find you do need something from the new BIOS version then best to make sure the system is assembled and running for a bit (even if that is just running in DOS mode or running memtest to ensure things are stable) so you know it is not going to shut down during the Flash (since a power loss during the Flash can make the MOBO unuseable) -- Also not a good idea to try the Flash if there is bad weather (I know we are in the middle of a storm that is covering much of the US today !) which could cause a power outage also.