[Xenon]

the last problem you cannot change, browsers aren't able to show html code parsed in titles....

the other problems:
you have to add those changes also in editpost.php

and also in editpost
find this:
$postinfo[title]=$threadinfo[title];

change it to:
$postinfo[title]=iif($bbuserinfo[usergroupid]==6,htmlspecialchars($threadinfo[title]),$threadinfo[title]);

then it should work