simple data entry web application

I am looking for a simple web application with following features. 1. It will have a screen to capture data. Totally there will be 22 colums , initially the records will be populated with 7 columns with available data like name, age, date of birth, cell number, address etc. Then after launching the application the field executives will go and capture remaining information for 15 other columns. 2. At any given time the field executives should be able to change the data. 3. There are totally 1,50,000 records currently and it may go upto 5,00,000 records in future 4. At any given time about 10 to 15 concurrent field executives will be updating the records/data 5. We should have a capability to filter the data based on certain criteria like age+caste+income and display the output on the screen . 6. By default we must have the ability to display all the records by alphabetically sorting on the basis of their name on the record IMPORTANT: A) We are expecting this application to be very very simple. The screens must be easily adaptable to the field executives so that they can capture the information easily. So ideally php or word press or any other simple technology must be used,. B) We need the freelancer to come up with resource requirement of database size, memory requirement for supporting 10 to 15 concurrent field executives , display of the records in a fast possible way on the screen based on filter criteria or the default screen itself. C) This is going to be on public domain the application must be secured so that the data is lost or stolen.