Problem with image sizing and Disqus comment threadbox

Here’s my site, http://valueacademy.net/

On the homepage and on the blog entries the images don’t stretch the fit the whole screen which results in this weird effect: http://puu.sh/nd1xI/45b72eaa89.jpg

Also, the disqus comment threadbox seems to be too big for the page where some parts of it is cut off: http://puu.sh/nd1D1/00ccd7b8bc.png

Any help in regards to this would be awesome, thanks!