WordPress: Create Form
It has been a very long time since I worked with WP,.. and I never got to working with custom forms which could be exported to Excel.
Is anyone working with Forms on WP? And what are you using?
If you are looking for export, the format would be CSV (comma delimited values). Excel or LibreOffice Calc will use that as a native format.
Never used WP forms, though.
Use Drupal. It's almost purpose built for this type of stuff. Custom content types and views make anything possible.