Your first question is not clear enough. As I understand you want an image on Blog page in the title. If so, enter the Blog page and set the image in the PAGE TITLE OPTIONS http://prntscr.com/kgmikv
As for the line on the screen, please navigate to the Theme Settings > Footer > delete the HTML ID from the pre-foot area: http://prntscr.com/kgmkxp
Could you please check how it works with some default WordPress theme like twentysixteen and default button element to understand is it our theme issue or not?
When you switch from one theme to another you can lose your setting in widgets. All the rest will remain. You would better to make the full backup before you testing anything.