Drupal Rule to Clear a Field But Still Retain Data? Need advice on fufilling this use case:

Use Case: 

When User edits the node the first time, he populates Field A, a text area.  The data from Field A is eventually displayed on View A.

When User or other User returns to edit the same node, Field A is cleared for convenience, ready for new text input. (But the original data is still in the DB, and displayed in View A).

When the User saves the page this second time, the new data replaces the previous data in View A.

Plus: Eventually,  I also need to display the history of Field A in the application from all the saved edits.
Use hook_form_FORM_ID_alter() with FORM_ID = node_form.

Example:

function your_module_name_form_node_form_alter(&amp;$form, $form_state) {
  $form['field_a']['#default_value'] = '';
}


For the second portion of your question, look into Node revisions.