Remove bloatware on Galaxy S2 - what are my options?
A backup never is a bad idea, so right after you get root access, you should:

Do a full NANDroid backup (which creates images of your partitions, so you always can revert to this state by simply restoring them)
Use Titanium Backup to make a full backup of all your apps and their settings (so you can re-install a selection when needed)

Freezing does not remove anything, and it is fully revertible. I always recommend to first freeze a single app, then check for potential side-effects, and only remove it if there were none. Titanium Backup even offers to create a homescreen shortcut to freeze/unfreeze an app (like a toggle: If frozen, the app gets unfrozen and vice-versa), which is nice for apps you rarely use but which always annoy you (for me, this is Google Maps, which I need maybe 2-3 times a year but is running permanently in background -- so I freeze it when not needed, and simply unfreeze it when I need it).
Basically, freezing an app simply hides it away from all activities. I'm not sure how that works technically, but I compare it with the &quot;execution flag&quot; of a Unix/Linux binary: If not set, the binary does not get executed. So no background services or any other activities from this app, though it is still installed.
In short: Freezing is the safe variant, as it easily can be undone. It also doesn't touch the apps data. Removing an app is final: without a backup available, it's simply gone, including its data.

Additional ressources you might want to look up for this topic:

Unistall a system app without root?
How can I uninstall applications that are locked by phone vendor?
How to Remove / Disable the Bloatware Apps in the HTC One X
Bye-bye, bloatware: Disable system apps in Android Ice Cream Sandwich