Teeechniclaly this is a Mocha setup issue.
First up, the error message is from trying to use the simple contact module more then once on one page. It was never initially designed to do this, and with many modules, not just ours, it is hard to get multiple instances of them on one page. For the time being, I have disabled one of the simple contact modules to move forward. I can see if this is something that can fixed.
2nd issue. Nothing showing up when clicking user. This is due to "configurable sidebars", a feature we have put into our templates for some time now. What it does, is allow you to totally disable or enable modules for a component sitewide. (say for instance you want a right module on your entire site, but not on the contact page, you can configure this manually in the templates index.php file.) It causes a bit of confusion however.
I changed it from contact-sidebar, which is not a option, to contact-right, which is. You can play with it further to get a feel for how i works and what it does.
This fixed the issue of the blank page.
Issue 3, a 6th tab. Where do you mean? I do not see any tabs on your site, unless you mean the navigation links. Not sure.