Post image (featured and in post) + color on first/newest post

I have three questions. 1. News/post image on the front page, seems to be the same size as the featured image (533x533) not as it says in the instructions on this site - post thumbnail (1148x574). 2. How do I not get the featured image in the post it selfs? 3. How do I get the first/newest post black as you have in your demo??? My page is: http://www.svenandresen.com/