Would security improve using Firefox extensions with the Tor Bundle (as Ghostery, HTTP Everywhere, Disconnect, DoNotTrackMe, Adblock Plus, Privdog... etc)?
The goal of the Tor project is anonymity. Your physical location and your operating system are obscured. Unless you provide personal data you will be anonymous.
Strictly speaking, privacy is maintained by Tor's SSL support. Having an encrypted link between your browser and the server you are communicating with is what maintains your privacy.
That said, plugins might increase your privacy by limiting interaction with adservers or tracking devices, but they diminish your anonymity by changing how your browser behaves. (See this stackexchange's fingerprint tag for related questions or check out the EFF's panopticlick project).
Given the Tor's goal of providing anonymity, the standard answer to your question is to recommend that you not install additional plugins.