Salvatore,
The manage_pages permission is required to be able to post to a Facebook Page on a user's behalf. To ask that permission of any 'normal' users on your site, you would need to submit the app for approval to Facebook.
However, if the only Pages you want to post to are owned by the administrator of your Facebook Application, you don't need to submit it. You can request any permissions you want from your admins. The manage_pages permission will only be asked of users that you've setup a Channel for, and no one else, so most users will never see that permission prompt.
I hope that helps explain, but if you have any other questions, just let me know.
Thanks,
Alex