Hi there,
You shouldn’t edit cornerstone content in visual composer, or visual composer content in cornerstone. That will break your page.
As the background, it’s stretching because it’s trying to fill your screen width. You should use a bigger image that can match your target screen size. Though I can’t really confirm your issue, I don’t see any background image added. Please add it according to your screenshot so we could check what’s the real problem.
And for the title, it’s because of this custom css that hides all titles.
.entry-title {
display: none;
}
Please remove it if you wish to display your titles.
And you may change your blog layout to masonry at Admin > Appearance > Customizer > Blog > Layout.
Hope this helps.