How to allow user's of a certain role to change the node creation date
You want Override Node Options module. 


  The Override Node Options module allows permissions to be set to each
  field within the Authoring information and Publishing options field
  sets on the node form. It also allows selected field sets to be set as
  collapsed and / or collapsible.


In addition you may be interested in Date Popup Authored to use a datepicker on that field.