Time Machine, External Drives, and Bootability

...Not sure bootability is a word, but I'll explain.

I have a MacBook Pro 2.66GHz. I was told by the Apple store that its hard drive is dying, but I really don't have time to drop it off. I have everything backed up, but the computer is otherwise fine, and what I'd like to do is this:

Purchase an external drive (preferably ~500GB) and create a bootable copy of my drive on there. Likewise, I'd like to start using Time Machine and be able to plug it into that drive each night so it saves everything.

My questions are:
1) Is this a good idea?
2) If I create a bootable clone, will it be simple to activate? For example, let's say my computer is dead now... How do I boot it up using the external drive?
3) Can I use Time Machine and the bootable clone together, or are they separate?
4) Will I be able to save all my applications (including obscure ones in Dashboard, along with ones I no longer have the disks for)?

Thanks!

Yes however use SuperDuper or CarbonCopyCloner to clone to external which will then be bootable. Time Machine is not bootable. You boot from an external by going into System preferences and selecting in Startup Disk or by holding the Option key immediately after the chime using a wired keyboard.

All aplications will be saved by cloning. It make a perfect copy of your current drive.

Well ... "perfect" may not turn out to be true. It depends on why the drive needs to be replaced in the first place. Presumably it's because it is failing, which means a clone may not be able to be completed and only the Time Machine backup will be able to restore (because it's only backing up the small changes that are happening now, not the whole drive).

Just sayin'.

Could you give more details on how I'll boot up the clone? I'm asking now because I don't want to have to go to a net cafe to log onto Mac-Forums and ask then while waiting for a response if/when my drive does go.

I've had a hard drive fail in the past, and nothing happens when I start the computer. Let's say the HD is totally dead, the computer turned off, the external plugged in, and the clone established... What steps will I take to get to boot up with the clone?

I saw another thread on how to make the clone, and I have Carbon Copier now. Really appreciate the advice, guys.

This article should clear things up Starting from an external USB storage device (Intel-based Macs)