cannot login via facebook connect

Error
The words you typed did not match the ones displayed. Please try again.

This likely means you have an additional captcha feature installed on your site. Please try to disable it if you do. JFBConnect works with the built-in Joomla captcha, but other extensions that try to perform a captcha check on all registrations can cause this issue. Specifically, if you're using K2, disable their captcha feature in their options as it's known to cause problems with 3rd party registration extensions.

For google connect i get the following
Warning
We were unable to retrieve your Google account information. Please try again.

Can you enable the "Use OpenID if No Google+ Profile Exists" setting in the JFBConnect -> Configuration -> Google area?
If that doesn't work, in the Configuration area, set "Enable Debug Mode" to "Yes". If there are additional error messages during registration, let me know what they are so we can investigate further.

For linkedin i get the following
Invalid redirect_uri. This value must match a URL registered with the API Key.

Please go over the LinkedIn application setup guide again. Specifically, make sure that step 3-D-b is correct for your site.

I hope that helps get you going, and good luck with your launch!

Alex

Can you go to the standard Joomla registration form on the page below:
/index.php/using-joomla/extensions/components/users-component/registration-form

At the bottom is:

Enter the two words you see below

Then, there's nothing there.

There is obviously some sort of captcha enabled on your site. Again, I think that's K2's captcha, and it's obviously not working as there not any words displayed there, or even an input box to enter them.

You'll need to determine what is trying to perform captcha on the registration page and disable it. The first place I'd look is K2's settings, as noted above.

I hope that helps,
Alex