There's actually 4 versions of Debian:
oldstable (currently squeeze) - as the name implies, it's the last version of stable after a new version has been released.
stable (currently wheezy) - this is what you downloaded
testing (currently jessie) - The next version of Debian, will be fairly cutting edge until ~6 months before the release when it hits the freeze and will progressively get older and older in preperation for release.
unstable (always sid) - as the name implies, this is not recommended for any system where uptime and stability is important.
Firefox is renamed Iceweasel in Debian due to trademarks. While Firefox is fully open source, the name and icon are NOT open source, they are trademarks of the Mozilla coorporation. So Debian, who maintains that the "main" repository can only be FULLY FOSS, therefore cannot run Firefox named Firefox. But it's exactly the same software.
Last edited by Timothy Miller; 01-26-2014 at 06:50 PM.