Comment 18 for bug 393978

@José Lou Chang

You would need to disable the daily ppa in Software Sources, update, remove firefox-3.5 and then reinstall.

@Sohail Mirza

This is not the place to have this discussion. You can come into the #ubuntu-mozillateam channel on irc.freenode.net if you want to discuss specific (non-bug related) issues.

As for what you asked:
It's not being branded per this document:
http://www.asoftsite.org/s9y/archives/161-FAQ-Why-is-my-firefox-3.5-still-called-Shiretoko.html

firefox-3.5 is a new piece of software in Ubuntu, not a version upgrade

Bug 396786 is open for the default theme missing.
Bug 390077 is open for the Google icon.

As for sharing extensions and plugins with the different versions, it is the policy of Ubuntu and Debian to include one copy of a library or program and use it globally throughout the system. The extensions and addons should be updated for Karmic and are most likely compatible with both. There is nothing stopping you from installing them directly in your profile, but the system versions will be shared.