You can add the sidebar by editing the page you want to add it. Go to WordPress Dashboard > Edit the page you want to add the Sidebar > in the Page Option https://imgur.com/a/lTlyRqQ found below the content area.
Change the Page Layout option, Set the Page Custom Sidebar.
After that you have to set the widgets in the Appearances > Widget.
1.I think the images that you have to upload need to have the same size that one we have uploaded to have the same visibility on the page. Our images are about 613px in width and 613 in height. You can upload smaller or bigger images but need to be in a square format.
2. About the Shop and single shop white space on the header can be removed by set the page Transparent on the Page Option. Edit the page on the back-end and change the option Header Over Content > Transparent https://imgur.com/a/lTlyRqQ
3. The sidebar on the shop pages aren’t included in the default design. You can add it but it will doesn’t look good except categories. You can also add the sidebar into the page option i have explained you before.
The image need to be bigger in height, the other images are 400 – 600 px in height and in the one with the problem the height is only 293 px. If you a upload an bigger image the problem will be resolved.
First i recommend you to update the theme to the latest version 1.6.4. Anyway i think the problem is caused by some plugin you have installed. Please try to disable and third party plugin that aren’t included with the theme. Disable them one by one to identify which of them cause the issue.
I have checked the issue that you have, i tried to deactivated your child theme and anything works perfectly. The customization that you have made create the issue with the menu.
So i recommend you to use a new clear child theme and add the functions one by one, so you can find which function create the issue.
