If I am reading your post correctly, you want to allow people to create pages and then also allow them to add in links in your navigation area.
Powercms2 will allow you to create dynamic pages from a template, so that part is easy.
There is nothing really built into pcms2 to deal with the navigation. here are 2 ways I got around that
1st way i tried it was I created an editable page(not from a template) in pcms in which I simply used source view so users could add their links to the new template driven dynamic pages. then I simply added that developer code snippet to my navigation area. That way works fine for my clients who have a basic unsderstanding of how to add unordered list items and applying the needed span tags and classes to each item, so they will pick up the proper css for the css menu writer.
then i have some clients who really don't understand that so I had to go a step further.
the second way was I saw this menu manager
I made my own version and integrated it into pcms2 so that it is very very user friendly.
The way mine works is that the user can add a page name and url.
then it adds the page and you can drag and drop it anywhere inside the existing site tree.
Once they have their link where they want it, they just click a publish button and then I have php rewrite the menu.php page that is included on my pages to show the new navigation.
I have php go through the list to detect what level location everything is now and automatically add in appropriate span tags and classes before it writes the new menu.php.
That script i mentioned above was like 9 dollars, I didn't buy it, but it may be configured in a way that you could adapt that pre built one to fit right in. I just saw it and it inspired me to build my own.
I still use pcms2 to have the client make their template based pages....this is just so they can add the navigation links to the drop down menu.