How to override "Create @bundlename" text?
You can try using Node Add title module ...


  Above module allows you to configure the title of the Node Add pages
  and the Node Editing pages.
  
  The default title of the page where users create new nodes is
  constructed by Drupal in a dynamic way that not always looks good. By
  default Drupal concatenates the word Create and the name of the
  content type. The result could be something like "Create Basic page"
  or "Create article". This is not always acceptable.
  
  With this little module you can replace Drupal's default concatenated
  Node Add page title and the Node Editing page title with a title of
  your choice for every content type.
  
  After installing this module you will see the following two new fields
  at the bottom of the content type configuration form:
  
  Node Add page title Node Edit page title Use these two new fields for
  overriding the titles of the new node creation pages and the node
  editing pages.


PS : Module is in Dev Version.... Test before you use..

If you are interested to change same using code you can use drupal_set_title

function mymodule_form_alter(&amp;$form, $form_state, $form_id) {
    if($form_id == 'mynodetype_node_form'){
         drupal_set_title('My new title');
    }
}