developing excel forms and database

We have a number of assessments that have been developed in excel. The assessments include weightings etc. so they do not port well to third party assessment tools. We do not want to share the assessment workbooks with clients - so need to move the data entry to the web. We want to develop web based forms to accept the data and populate the excel workbook. the excel book will then be saved for that client and some of the data pulled out of the workbook and moved into a database. we also need to store documents that the client sends us that support their answers in the assessment.... a short explanation