No there is not a feature that allows admins to edit others sites..the only way is if you go into your database through your hosting control panel or use php myadmin and alter the database..the html code/colors is saved in the database.
and yes I agree it is really needed.
I'm not sure why you would want the website icon visible in the pm system...but if you search back in this thread there are instructions on what the code is for the icon and how to add it..you can find the code in viewtopic_body.tpl or profile_view_body.tpl as well.
I wouldnt expect much help from the author on the existing mod..he's supposedly re writing the entire thing from scratch but it will be a long time coming..hes a moderator here now and seems this mod is not a priority to him any longer...happens with alot of phpbb2 mods.
I'm sure someone else will either take over development or write their own sooner or later...sure would be nice.
also I think many mod authors are anxious to see if any BB2 mods will be compatible with the upcoming BB3 release...whenever that finally happens...lol
I agree with the fact that an admin editor would be preferable, however, i believe that this feature is not of great importance and that other features precede this, even though ppl who dont know how to use phpmyadmin may have trouble editing their users' pages.
although i agree with most things you have said about the author, he is still supporting ppl and this mod is still active. Ppl are free to contribute to this mod and if battye wants this mods to be completely taken over by someone else, he would probably say so.
it will not work with phpbb3 without being modified.