removing wordpress generated code from the head section?

1) Normally not (that’s the translation mechanism offered for javscript strings), but you can probably de-register that l10n script. But be warned that some plugins and the site might not work as intended any longer.

2) Yes, by uninstalling the contact form 7 plugin.

3) Yes, by removing the disqus plugin.

4) If disabling the admin bar did not work, please report this as a bug in wordpress trac. I assume it left’s over a registered hook to be removed, but that’s just an assumption.