Basic PHP/MySQL based CMS

I need a basic, PHP/MySQL based custom CMS built from the ground up. However, some of the features can use free open source scripts (such as rich text editor, media library, calendar, etc.). Needs to be extremely secure and properly coded to not allow SQL Injection, Cross Site Scripting, etc. No graphic design is needed for public-facing site. The CMS should support the following areas/sections which can be plugged in to any front-end design. • Dynamically generated navigation bar to display links to pages (with multilevel dropdown menus) • Calendar of events • News and Announcements • Site search • Image upload and media library • Image gallery • Embedded videos (Youtube, Vimeo, etc.) • Contact form with Google map • Member registration (multilevel) • Search engine friendly URLs • Ability to create unlimited page categories (at least 3-level deep) • Ability to create unlimited pages with option of selecting any page template. (Template design is not needed.) • Preview page before publish • Date-based publishing of pages • Ability to un-publish and delete pages Please only reply after reading the requirements and if you are an experienced developer. No auto-replies will be responded to. Thanks.