|Q#01: What does this MOD do?
This MOD makes it possible to prevent users from viewing the unapproved posts until the contents has been approved by the moderator(s). The MOD can be used to combat spam bots that make random posts in the public forums or for extended moderation in any forum with sensitive topics (religion, politics, etc.) where post screening is required to maintain forum integrity. The MOD is quite flexible in its settings and allows you to configure various approval options per forum.
Q#02: How can I define who can post freely and who requires approval?
This MOD is very flexible when it comes to setting the approval permissions. It allows 3 main approaches to define who is allowed to post freely and who isn't: by setting forum's approval options, by setting user/group approval permissions or by setting ranks approval option. All of these can be combined to fit more specific requirements. Additionally, there are some extra options that can affect the approval decision making, such as 'Approval for new topics only' (and not the replies to them) or 'Topic starter can approve topic posts'. All of these features are discussed in more detail in the documentation. Also, see the next two questions for the real life example of approval settings combinations.