Change WordPress Page to Post
UPDATE wp_posts SET post_type='post' WHERE post_type='page' AND id=X
Change WordPress Categories to Tags
UPDATE wp_term_taxonomy SET taxonomy='post_tag', parent=0 WHERE taxonomy='category'
Change WordPress Page to Post
UPDATE wp_posts SET post_type='post' WHERE post_type='page' AND id=X
Change WordPress Categories to Tags
UPDATE wp_term_taxonomy SET taxonomy='post_tag', parent=0 WHERE taxonomy='category'