1) Can the clients that login to their page create a new page or a duplicate of another and then add a button to the menu? Is this possible?
2)What are all the add-ons compatible with this product? So far I see the following:

• online editor,
• online page editor,
• file manager,
• php upload, &
• smart image processor..

Hello Mandy.

1.)Please take a look at the product manual which will guide you through the functionality and the user interface of the extension:
Advanced HTML Editor 3 Manual

You can locate very useful tutorials about the various ccombination with other of our products under "Videos" tab from the product page.

2.) The available add-ons are :
Online Page Editor Add-on
Image Gallery Add-on
YouTubizer Add-on
Picasa Gallery Add-on
File Manager Add-on
DMXzone Nivo Slider
HTML5 Slideshow
DMXzone Google Maps
Google Maps Drawing Add-on
PHP Upload add-on which is combined with php upload and smart image processor.

Can you just answer my 1st question whether or not you can have a client login and add a page themselves without me having to do it behind the scenes?

If your question is :
If you can create only the index.html file for example and your users to be able to create the other pages when the editor is inserted ot that page , for example about.html.
No , unfortunately this is not possible.

Regards:Vulcho.