Also, everytime I add something to the main sidebar it turns into a “Skinny rectangle”, as shown on the screenshot: http://awesomescreenshot.com/02264si12c
I believe it might have something to do with the html code used to build the box.
1) Go to Theme Options > General > Breadcrumbs > here you can find all the settings for this area – paddings, background, color schemes etc.
If you want to use different images for different pages you may upload featured image for your page and it will be displayed in breadcrumbs. Also, every page has its own breadcrumbs settings, edit page and scroll down to 8theme – Layout settings.
2) You have added 8theme – Static Block widget into main sidebar and selected prefooter static block that has 3 columns layout. That’s why you see that small block. Either delete this widget if you don’t need it at all or if you want to change static block go to Static Blocks > edit prefooter block and its layout. Don’t forget to enable VC for static blocks https://www.8theme.com/demo/docs/xstore/#theme_settings_44_static_blocks