WordPress.org

Can I use this plugin along with the reCAPTCHA plugin for comment spam?

Sure. Just activate and configure that plugin first, Recapture second.

How do I know that it's working?

Are you still getting user registration spam? If so, please let me know. If not, failed attempts at the reCAPTCHA are logged to the Recapture Configuration page, so check there.

This is the worst plugin I have ever used, can I send you hate mail?

Sure, the address is ben c masters at gmail dot com. Though I would much rather hear about specific problems you have encountered while using Recapture, and some possible suggestions for improvement.