What are the exact steps a user must take to become a friend of another user?

Click on the link to add as a friend and then wait for that user to accept your friend request.

Is there also an easy way to control or synchronize the friends-lists from another module? "Easy" means that I could write stored procedures doing the synchronization for me without messing everything up ;-)

If "Easy" for you is writing a stored procedure then yes you could. We can not provide support in this area however.

Suppose you accept me as a friend. Does this automatically mean that we can both see each other's profile? Or do I also have to accept you as a friend?

Steven,

Currently no. But we have provided a script in the forums that handles two way friend adding.

Thank you. I did a search, found the script and will install it. Apparently there is a "script repository". How do I find this repository to see of there are other useful scripts? Thank you.