case 1

Hello Mr User. I see the problem. We can fix this issue looking the article *removing gaps on your site* in the WIX help center. This article tell us that to remove a gap on your site, you have to click the Zoom Out & Reorder icon  on the top bar of the Editor. Then for the blank space you have to click on *delete space* And your issue will be fixed. for the last problem on the last line you dont want to be on your site just go to pages and choose the page you dont want the line, then click on the 3 points icon and click settings and go to layouts. For the las click on no header no footer and the line will disappear.
Here is the article https://support.wix.com/en/article/wix-editor-removing-gaps-on-your-site