Photoshop Background layer

The background layer is locked by default. When I unlock it, PS creates a new layer layer0 and deletes the background layer.

Is this a bad thing to do. Does the background layer have any special significance or properties that it shouldn't be deleted/replaced? Should I instead copy of the contents of the background to another layer and leave the background layer alone?

I noticed that when I open an image, PS automatically puts the image on the background layer. How do you handle opened images before working on them.