'Requested By' field
When project requests are submitted by webform it will always use the user who generated the webform for the 'Request By' field. Some customers have created a required text field for webform submissions called something like 'Submitted By' that the submitter will manually fill to show who the submitter is.
Project Requests fields visibility
It is not possible to make a field visible in the project request type in Daptiv, but not be visible in the web form. The suggestion we can give is to make the fields that you absolutely need to be required and at the top.