How do I re-import menus and blocks? I've got a local install that has turned bad. I want to quickly re-import block settings, block content, and menus.
How can I achieve this?
You can export blocks with the Features Extra module, or better yet, use the Boxes module, which is designed to be exportable.

Using MySQL dumps is an advanced trick that gets harder with each version of Drupal as the API becomes more complex. It's not recommended and definitely not for the faint of heart.