Interactive website - front end and back end

I'm looking for a bill tracking site with two primary areas - an employee area and a subscriber area. In the employee area, employees would add legislative bills, upload documents associated with bills, update bills, add tags, etc. In the subscriber area, users could search on bills, add bills for tracking, and view the bills that they are tracking. Users should be able to be notified by email when bills are updated. There should be a straightforward means for adding/editing users. The employee/back-end side should be user-friendly enough to handle a relatively high volume - they'll be adding/updating many bills on a daily basis. For now, I'm looking to get an idea of timeline and basic implementation plan. This is a bit larger project than I would normally take on, so I'm looking to subcontract. I'm mostly interested in the architecture/functionality, not so much the graphical aspects - I can move forms around if they're not in the right spot. Must speak English. Strongly prefer if this is done in PHP. This will be targeting a Unix based server that we don't have full control over. The client's current setup is a shared hosting environment. It's a local hosting company with their own servers, so there's some flexibility, but no guarantees.