All the homepage options are set in the Customizer.
The main homepage feature is the onepage scroll. For this to work properly you need to setup a menu as detailed on the getting started page.
The Section Spacing is a CSS instruction. The format is:
If you don’t want any gaps the default is:
The border uses a similar structure:
border-bottom: 1px solid #343848;
where the hex number is the colour of the border.
If you want an image background on each page check the featured image box. You can then add a featured image to each page and it will appear in the background. Top Tip: the image you choose may well make your content difficult to read so you may need to tweak the site colours (in the Customizer).