On the Stream Isolation page, there is a list of applications that are pre-configured to use socks proxy settings using application configuration files. If you want to disable this…
You must go to the applications settings and remove what Whonix has applied by default.
For some applications this is impossible.
sdwdate
TorChat
Can I surf with proxy without that they cause problems or I need to disable them? (sdw-date start just at the beginning{I setup the proxy after}, while I dont use torchat)
Last question: 
Now, I’m not more anonymous (fingerprint), are the differences between using iceweasel or Tor browser the spoof of OS, web browser, screen size, OS cpu, language etc…, or are there other problems like leaks, stream isolation is break (It seems also in Tor browser) etc…?
Regards