Linux advice?

Okay, I have here on my desk an external hard drive big enough to copy my entire installation onto, rather than just backing up the data.

Questions, then:

1) Should I do this?

2) How do I do it?

3) Should I make it bootable, and if so, how?

4) What other questions should I be asking?

[En passant: it makes little buzzy-clicky noises, which are very quiet and discreet but none the less New Noises on the Desk, and I find myself very aware of them. That's probably a good thing. One should be aware of new toys, for at least a day or two. Hence all this how-can-I-use-it-best anxiety.]

In which I am weakened

I fear I have become a wimp, in the twenty-odd years since I used to bake regularly. Ten minutes' kneading doesn't half make my arms ache. In very particular muscles, that I clearly don't use else. And one loaf a week isn't likely to improve that very much...

Still. This week's loaf is looking even better than last week's. Currently cooling a little, before I cut it. Now would be a good time to heat the soup. 'Scuse me...

Oops

I appear to have made a batch of breakfast rolls.

For the sake of clarity, that is I-who-do-not-eat-breakfast.

Damn. But it's so much fun, this baking...

*eyes breakfast rolls anxiously*