PHP custom implementation related to Excel

I need a small php project that allows me to upload an excel file and allows me to store them in a list sorted by date with a custom comment, to allow my customers downloading these excel files. When the file is uploaded using the form , we will need to make small source changes in the excel rows and columns. Task : Turn a columns V and W that will have these values "2012-10-17 08:00:54" and convert these values to these ones "17-10-2012 08:00:54" , process file and update to the list.. so we can download it later fixed. This is a first subproject.. I will request more modifications in next weeks. Developer can use [login to view URL] for example for excel file manipulations.. or whatever. All texts and captions for this small application will be loaded from a XML file, this will allow me to translate it. (GUI) Requeriments + Add login page + Upload page + Download page + User managment (username, password, email, active (yes/no), user level (2 user types) + Administrador = will be able to upload files /download files, delete, modify and place a file download time expiration timestamp + Normal user = will be able to download files + PHP5, MySQL5