PDF file catalogue LAMP web app

OUTLINE
Second iteration of an Apache, PHP mySQL based system for secure delivery of sets of printable educational flashcards.
The first was posted here but never got close to starting as the client regarded it as too complex. He is in total agreement this time round and requires a speedy response.

The app will handle A4 PDF files stored in a directory in the web server referenced from a mySQL database which also holds metadata about the set.
(or stored in the database directly, whichever is more efficient, there are over a thousand files and there will be more)

It will have .. (more details in attached file)
a login system with 2 kinds of users ... "Admin" and "User"
a file browser
a file manager
user management
and messaging

The Interface is already designed... it is in Spanish, but this will pose no problems as the project manager is bilingual English/Spanish