How to edit/ add items to the registration form?

[Reycer]

All you need to do is log into your admincp--->settings--->Human Verification Manager and tick the radio button that says "Question and Answer Verification"

Click add new question, type in any question or type in something that is to be repeated.

Click Save, now click on "Add New Answer"

As per your second part of your question:
admincp--->settings--->options--->User Registration Options--->Moderate New Members "yes"