1. Writing a disc in "disk at once" mode closes the disk and nothing else can be written to it (at least normally and officially, but there are technical ways around this).

2. Writing a disc in "track at once" with the option "do not finalize, leave disk open for more writing" actuallty writes a blank next session header, which is what is needed to add additional sessions to a disc.

3. I don't know if Roxio offers these options, I long ago stopped using it's predicesors. If it doesn't then this would be just another reason in a long list not to use it.

4. None of this has much to do with Knoppix. Knoppix does not allow you to write anything else to the Live CD.

5. Even if you could write to the CD, you would find that there isn't enough space for another session.

6. This is a trick that can be used with other live CD distros. For example I have burnt DSL to the first session of a CD (with Nero), booted it, and then used DSL to burn an additional session on the same CD. DSL only takes up about 50 meg on a disc. But that is not to say that DSL somehow incorporates the information that I wrote to the second session when it is next booted; it does not. DSL does have a nice klik-like package system and if you were clever you might be able to download a number of additional packages that you want, burn them to the second session, and later access them from the CD, but I don't know what else may need to be done other than just copy the files.