How hard is it to replace the iMac's super-drive?

Hello.

Recently, my iMacs superdrive has caused some trouble.

1. It makes lot's of noise with some (but not all) of the CD's and DVD's I put in.

2. It suffers both read and write errors, to a point I can't duplicate my original Snow-Leopard DVD, or even the bootable DiskWarrior DVD I own. I've lost at least 10 media by now.

3. The worst. It is unable to throw out CD's and DVD's. It starts putting them out, then "regrets" and they go back in, wait a little, and remount. I need to "help it" with a little thin plastic, and with that voodoo moves I sometimes (one in 10 tries) can finally let the CD/DVD jump out. I'm afraid I can ruin something in the structure of the machine like this.

So --- I need and want to replace the superdrive. My questions are:

1. Is it hard to do?

2. As you don't supply the part I need (a new compatible superdrive) where can I get it?

3. Some guidance for disassembling and reassembling the iMac?