Custom application based on sharepoint or other technologies

We are currently looking to develop an in house application which will allow us to run the day to day tasks of our business and move from a paper based system. The project will be an on going development and improvement scheme so a contract after initial software build will be required. We would like to develop the application using sharepoint though we are also open to other technologies however this will need to be a case provided by yourself and then viewed and tested from our perspective. Please see attached specification with full details and current scenarios. Many thanks and good luck