RESOLVED
i give here mys solutions to anyone interested:
– i forgot to restart apache (sig!) after installing the php-mysql module. shame on me!
– after that i ran into another problem : i just misspelled the commandline in mysql to create the password and strangely MySQL didn’t complain. i didi it again w/ PHPMyAdmin, and it worked.
BTW, stock MySQL tables (the myisam type) living in /var/lib/mysql/wordpress_db_name can be rudely copied from one DB to another. i.e. you don’t have to make a SQL dump, “cp -r” makes it.
<shouts> Big up to the folks at wordpres.org – your piece of code rocks! </shouts>