I had no time to make the further steps and every time my site crashes I loose clients, so I beware to be to busy exploring more safty :)
Now I deinstalled admintools, that worked in the backend.
Admintools 2.1.2 works with Joomla 1.6.5 but caused an php error message about
"libaries/joomla/filessystem" in the frontend. Some safe mode issue. I commented the time-limit line out (but do not know if this is an problem fpor safty) and now I have this problem only in the backend. Thats the error-message:
Warning: set_time_limit() [function.set-time-limit]: Cannot set time limit in safe mode in /home/.sites/494/site470/web/libraries/joomla/filesystem/folder.php on line 548
Additional I cannot update to the last Admintools via backend because no XML File is found.
My provider uses some fix so joomla works perfectly with safemode on without any problem with permissions. If you need more information about this - I never found that in use at clients hosters - I will look for it.
Thanks, Dan