1. I only want registered users to be able to post. no guest posting
You don't need a mod to do this, this is already a built-in feature in phpbb.
Go to your admin control panel, then under Forum Admin click on 'Permissions', then choose the forum you want to edit.
Once you have selected the forum you want to edit, make sure you click on Advanced Mode so you can see all options.
You will see that one of the options says 'Post', if you select REG from the pull down menu then only registered members will be able to post in that forum.