1) Because you tried to create footer using Elementor Header & Footer Builder plugin and created an empty footer. I disabled and removed mentioned plugin. Use built-in Static blocks option to create/edit footer content.
2) Add admin strings to string translator https://prnt.sc/1vpip7x
3) Use admin string translator if you add custom texts to the mobile panel https://prnt.sc/1vpjfik or store core plugin translation if you use built-in mobile panel items https://prnt.sc/1vpjnar
4) Use a string translator to change that text.
5) Disable all the plugins that you don’t really use because every additional plugin calls JS and CSS and slows down the page loading speed. Also, install cache plugin and use modification and combine options to speed up the site loading. Optimize all the images that you use, https://tinypng.com/ cool tool to optimize images.
One standard license is valid only for 1 project. Running multiple projects on a single license is a copyright violation.