Thread:Extension talk:ConfirmEdit/spambots still can create an account - but cant edit page

My wiki has been overrun by spambots. Thankfully because of this extension, these spambots are not able to edit the pages, but they are still able to create an account - about 50 new accounts everyday.

How can I change the CAPTCHA settings to stop these spambots? I use the question CAPTCHA - it is the easiest to use and install and I want to keep it without adding new CAPTCHAs.

Is there another extension I can add which will limit the spambots creating a new account?

These bots only create new user pages - can I block all users from adding external links - but only to user pages?

Thank you.