Installed 3.3 to the HD, read the security sticky.

The link suggests adding sites to download from, but should we add all 3 they seem to be for different releases?

After installing, I did a
apt-get update
with the original list then a
apt-get -s upgrade
and it wanted to install or upgrade 255 apps, some from differnt releases, should we do that, do I need to add sources to the list for security?

Can someone clear this up, I think 3.3 is a Woody (testing) release, not Sid (unstable)?