1) Possibly not; but testing is where it's at. Don't bother with unstable just yet. Change your sources.list to point to testing, do 'apt-get update', then 'apt-cache search apache' and see what turns up.

2) Java2 == Java 1.2, 1.3, and 1.4. There is no real Java 2. I believe that unstable has 1.4... I don't recall what testing has.

3) Bleah. Qmail. 'Nuff said. You're probably on your own because the licensing for qmail is wacky.

4) No issues. It's dead-stupid-simple. Modify your sources.list as above, 'apt-get update', then 'apt-get dist-upgrade'. Voila, you are now running testing. Again, don't bother with unstable yet.