Hi,
First of all, it's realy looks like your site has been "hacked", but it for Black Hat SEO purposes.
They usually inject links on the footer, but sometimes the code have conflict with the original page and then, the site renders without footer (take a look at yours).
It was probably done by a auto script, the injection can be removed and eveything can be restaured.
And coming back to the slider issue, it's a CSS problem with the flexslider, probably with the jQuery initializer of the plugin.
Also, the DroidSans font isn't loading, I can fix this too.