1. How often should I resubmit my site?

B. In most cases, never.

Correct - Go to Question 2

Source: The official How to suggest a site to the Open Directory

Procedure After Your Site is Submitted

Please only submit a URL to the Open Directory once. Again, multiple submissions of the same or related sites may result in the exclusion and/or deletion of those and all affiliated sites. Disguising your submission and submitting the same URL more than once is not permitted.

See also - Multiple Submissions