Hey, just wanted to say thank you for your help. I was able to figure out the issue with the mobile site. #primary just had to be set to width: 100%! That is for widths of 767px and below… Thanks! Still cant figure out the featured image thing but I discovered that I am still able to add them if I really want to in the future. This might help someone else that has the same problem as me in the future..
All you have to do is activate a theme like “sixteen” then you are able to add “featured images” to the menu items. Once you have added them to all the items you can active your theme. When you go to a menu item’s page you will notice that the thumbnails are still there even though you added it using a different theme! So, there is a way around it… it is just only a little bit annoying haha.

Thanks.