PHP, mySQL

We're needing a database to help keep track of properties for sale. Each property has about 70 fields spread out over about 6 tables - Original, Properties, Advertising, Signs, Status, and Closing.

There needs to be a secure place for authorized users to login with a username/password and manage/update the details of each property. They also need to be able to add add'l properties.

The properties need to be sortable by month and there needs to be a function that exports the entire database into an Excel Spreadsheet.

It is also important for there to be a backup/restore function, which automatically backs up the property record every time that particular property is updated.