There are many BIOS updates that have been released since after the currently installed update.
My question is: Do I flash them all in order one by one from older to newest, or do I only flash the latest one? (Does it contain all of the previous bios in one?)
It currently has BIOS Version 0601 installed and there were five new bios released since this version.
You should be able to just skip to the latest one, but it wouldn't be a bad idea to check any readme type files that come with the BIOS to make sure there aren't any special instructions.
That all said, up to you in the end, but I personally tend to tell people that it's not worth updating the BIOS unless the newer version(s) fix some bug that has been plaguing you, or adds support for a new CPU you want to use... Something like that.