A simple backup and archiving system

I bought the DAM book some months ago and read it with great interest. There's some good stuff in there. However, I find that it's much too complicated for my simple setup—I have about 3,000 images in Lightroom 2 at the moment.

I'm converting my originals to DNG and letting LR back them up to an external drive. Should I just manually copy them off the camera and arrange them into buckets? The LR backup merely arranges them into folders titled 'Imported on June 6' etc. This is different to any bucket system.

Since I already back up my entire computer to an external disk, is there any point in having LR do another backup? I could just burn the buckets onto DVDs. Would it be a good idea to then delete the bucket folders just to save disk space on my computer?

The other area of concern is derivitives. At the present moment, I work on only a small number of images from the entire collection. Therefore, when I archive, am I just saving another (slightly different) version of my original buckets?

Finally, the question of working on virtual copies. Since these are stored in my original LR folder—separate to any Photoshop files—how are they archived?

Hope all this is clear!