Hi Sam,
I see that you are using Catch Kathmandu Free Theme.
1. Your question about moving the menu down below the logo.
— For this first, you need to disable Header Right sidebar. For this, go to “Appearance => Theme Options => Header Options” and click on “Check to Disable” in Disable Header Right Sidebar and save changes.
— Then you need to create Custom Menu from “Appearance => Menus” and then assign you menu as “Secondary Menu” from “Appearance => Menus => Manage Location”. For instructions on custom menu see this http://catchthemes.com/blog/videos-blog/video-series-creating-wordpress-custom-menus/ and http://catchthemes.com/blog/custom-menus-wordpress-themes/
2. Your featured image size in those posts added in slider is smaller then required. If you see the theme instructions page at http://catchthemes.com/theme-instructions/catch-kathmandu/, where you can see the size for Featured Post Slider is Width: 1280px
and Height: 550px. Yes, cropping is done automatically if the image size is larger then this size but how can it crop the image smaller then 1280px width.
3. If you don’t want the sidebar and content in homepage, then first check in your reading setting at “Settings => Readings” and make sure you have selected “Your latest posts” and in “Appearance => Theme Options => Homepage Settings => Homepage / Frontpage Settings”, make sure you have not checked in “Enable Latest Posts”.
Regards,
Sakin