Wolfad 1: easiest would be to open style.css and replace all occurrences of #63c6ae by the hex color code of your choice. But this will not survive the next theme update so I’d highly recommend creating a child theme and doing the changes in there (your favorite search engine will help you finding lots of information and tutorials on this subject).
Alternatively you could use the Custom CSS section in Theme Options – Design Options and override the default color for selected elements like e.g. `.slogan-wrap { background-color: #DD0000; }
.page-title-wrap { background-color: #DD0000; }`
Or you go for the Pro version where color selection is included…
ad 2: I am not sure I got the question right – would you like to have a 2-column layout for your blog posts?