Drupal - How to export/import all nodes of a specific content type?

For Drupal 7, you have 2 choices:

• Node export:

This module allows users to export nodes and then import it into another Drupal installation, or on the same site.

• Feeds:

Import or aggregate data as nodes, users, taxonomy terms or simple database records.

Might be a late answer, but still I would personally consider it as the best option - please consider using migrate module https://drupal.org/project/migrate