This week's book giveaway is in the OCPJP forum. We're giving away four copies of OCA/OCP Java SE 7 Programmer I & II Study Guide and have Kathy Sierra & Bert Bates on-line! See this thread for details.
Yes, daemon threads can live longer than the thread that created them, as long as there is at least one other non-daemon thread in the JVM. There's no special link between the daemon thread and its creator.
The garbage collector thread, along with several other special-purpose threads, are all created when the JVM starts up, before any of your code is invoked.