It's important to have a backup...and maybe a flash drive in a safe. Which I actually just got a fireproof safe, so maybe I'll do that. Or a microSD card or something. But I'm not too sure about a key on a flash drive that's actually out in the open, unless it's pretty well encrypted. Flash drives are too commonly lost or stolen.

In regards to the live USB. Big ones are pretty cheap these days. 8 gig ones are almost standard, and that's actually perfectly find in size for a basic operating system setup. You probably want a bit bigger to customize with all your apps and games and regular documents. Though a lot of that can be put online too.

I actually think Keychain doesn't really save me any time. Most of the web apps use a cookie system and work with that other key system, which has already had a major security failure. It probably actually wastes more time.