I have just found a solution for the 2nd problem i mentioned (the "???" characters shoing instead of the Hebrew characters) :
I logged into horde as admin, went to the setup console.
At the "databse" tab i changed the Internally used charset to windows-1255 (the hebrew charset) instead of iso-8859-1.
No more "??????" !
Ah yes - the only thing is that i had to re-enter the contacts and calendar tasks to regenerate them with the new charset...
Can someone please dirrect me to find the translation file for Hebrew (po) ?
Amir