Section "Appearance"

A section "appearance" should be added to the Admin Center, in which some of the default settings for the lay-out of the front-end can be changed. Some of the settings in this section will be the amount of posts to display on the homepage, how many posts to display on an archive page…

This feature is rejected. Themes will have a default plugin once plugins are created, and these plugins will contain the configuration settings for these options. A theme plug-in may also want to add an extra configuration page to the "Themes" tab, in which these settings can be set on a theme-by-theme basis. More info is on the dev:themes page.