User permissions

Hi,

I have managed to add some basic permissions to punBB by adding an extra column to the users and forums tables called user_level.  if($cur_user['user_level']<$user_level (taken from forum database)) then display error.  so each column contains the user_level - 0 is lowest, 9 is highest.

however, i have two questions.  How can i hide forums from ppl without sufficient permissions on the index page?
Looking at index.php i think i need to change this:
$extra_sql = ($cur_user['status'] < PUN_MOD) ? ' WHERE f.admmod_only=\'0\'' : '';
but how can i add an extra command to that?

How can i hide these forums from the search (i.e. dont display topic names in the search field that people aren't supposed to be able to see)?
No idea how to do this...

Thanks

MrBarby