I'm searching now for the 2nd day for a good method to solve my problem. Many post where found but none did have a good sollution, so I'll try it again

- I already have a server running where users have to login (from .htaccess) to access the /Secure folder and all its sub folders.
- I'm using PHP for scripting.
- I've installed phpBB 3.0.2 in a seperate folder /Secure/Forum.
What I need is a way to auto-login a user as soon as he visits the forum, using the $_SERVER["PHP_AUTH_USER"] variable in PHP. A user won't need a password on the forum since this was already checked when entering the /Secure folder. In case the no password isn't an option, it could be pasted from the $_SERVER["PHP_AUTH_PW"] variable.
Related to this, I also need to update my current NewUser.php script to add an user entry in the forum's userDB, First thought was "That shouldn't be to hard, just enter a new record in the phpbb_users table", but I cannot find anywhere what the meaning is of several fields in that table. F.E., what do I need to enter in the user_permissions field for a normal user. In case each useraccount does need a password, I need to know how the password is stored in the forum userdatabase, so my script can generate this.
Also, how do I auto add a new user to some groups?
Again, I know that there are several related posts, but I really hope that someone can help me with some code-samples to get the job done.
Thank you.
Micha