You generally don't want to flash the original bios on the Xbox. Flashing the bios on a mod chip that has a flashable bios, or using an EvoX compatable bios on a mod chip that has an unflashable bios, is ideal.
You need a mod chip in order for your Xbox to even read a CDR with the EvoX software on it when you try to set it up. So, basically you MUSt have a mod chip, and you should read all of the tutorials on this site to get started. Even with a mod chip, flashing the Xbox's original bios is still not a good idea. You don't need to flash your bios with the EvoX bios in order to use the EvoX software.
As far as which mod to use, it all depends. The Enigmah is good, but requires you to solder 29 wires. The X-ecutor is good, but the bios on it isn't flashable. It only requires that you solder 1 wire. The Matrix/Xodus chip comes out on Sept. 21st and supposedly doesn't require any soldering. I appears to be fully featured, including a flashable bios. Nobody really has any detailed info on it yet, unfortunately.
EvoX doesn't automatically do everything you asked, but with boxplorer and xbcopy, you can copy your games to the Xbox HDD. It'll do everything else you asked without extra tools.
Good Luck!
