Layouts Manager uses master template for settings that are shared among different templates. This makes changing settings across templates easier. Master template is not used directly, but only to get settings for other templates that are set to use master settings.
Installation of themes based on xScape theme framework is easy and not much different from regular themes. First activated, theme will try to set everything automatically, but that can fail, and than you will get the error report with the link to the solution.
gMap This is easy to use module within the xScape Theme Framework that you can use to add Google Maps to your posts. You can set various parameters including adding marker with a note to mark the location you are posting about or you have traveled to.