PHP app enhancements

I have an existing LAMP application (PHP 4) now running under PHP5. I need 1. Input screen does not accept negative values in amount field eg. -1.05 2. Currently the system works by using a number eg. 0412204271 and period Mar09 in the URL to pull correct data to the screen. We need to add a new field tpo the table - UniqueID which will be populated with a unique generated id. We need to change the system so that it uses this unique id and the period to pull the correct data into the input screen. We expect tehse changes to be relatively easy for someone? with LAMP application experience. I will communicate and send the application code and database to persons that respond with info displaying that they are capable of completing these changes quickly without bugs. I will close the project quickly for the correct person.