**Solution to the 2nd problem:
Open invite.php from sources directory
Change
if(mail($email, $subject, $message_final, $webmaster_email))
with this
if(mail($email, $subject, $message_final, 'From: '.$webmaster_email, '-f'.$webmaster_email))
Now i have 3 little problems...
A- Is there a way to hide the invite tab from members who are not allowed to send an invitation?
B- It would be SOOO HELPFUL to put more than one email adress into the "Send Key Via Email" form. So i can send multiple invitations to different adresses at once.
C- Why invitation email shows turkish characters as JAPANESE characters?