Sorry for not getting back to you sooner. First, I just tried to register on your site using Facebook. When I did, the FB popup had the following message:
This app is in sandbox mode. Edit the app configuration at developers.facebook.com/apps to make the app publicly visible.
You'll need to go to that URL and set the "Sandbox Mode" setting to "Disabled". That's the only setting we can't control with Autotune, unfortunately.
Regarding the captcha, I see the same behavior you mention where the image isn't showing. However, I'm not sure what JFBConnect is doing to prevent that behavior. We'll need to get Alejandro from jReviews to help narrow things down. Basically, from what I can see from doing a good bit of debugging on your site:
1) The form loads and calls:
var initiliazingForm = jreviews.dispatch({method:'get',type:'json',controller:'common',action:'_initForm',data:{'data[form_id]':form_id,'data[captcha]':captchaDiv.length}});
2) That load seems to be generating an AJAX request to the below URL (but I know something is wrong here, because that always comes back with a 404):
index.php?option=com_jreviews&format=json&tmpl=component&lang=en&controller=common&action=_initForm&form_id=jr-form-review-0&captcha=1
3) After that AJAX call is complete, the following is *supposed* to be triggered:
initiliazingForm.done(function(res) {
form.find('span.jr_token :input').attr('name',res.token);
...In that block is where the captcha image is inserted on the page.
Something between that AJAX call and the response is preventing the captcha from being replaced. However, I don't know JReviews code well enough to understand what the response from the request above should be. If it's possible to get the jReviews devs to let me know what the actual direct call above (that I'm getting a 404 on) is, I can try it and see what the 'bad' response is. That should be enough to get a PHP warning or something that would explain where things are going south.
Finally, for the MySQL messages you show above, I was never able to recreate those. If you're seeing those, they could be the cause. I (again) don't know where those would be coming from in JFBConnect as we haven't heard of that PHP notice before.. but narrowing that down may solve the issue as well.
I hope that helps get things started,
Alex