Click the Import button on the Subscribers page. You can import a list of contacts either manually or by a file import. To import manually, type email addresses or social IDs into the Import Manually box, one per line, and click Import. To import a file, click Browse to select a CSV file from the Import a File screen, and click Import. The CSV file must contain at least one column Titled Email, Twitter, Facebook or YouTube in order to import successfully.

Yes. Go to the Subscriber tab, select the list or subscribers you want to export, and choose Export from the Actions menu on the right side. Your subscriber list will be exported as a .CSV file.