Hi there,
1. change your meta text and link colors in Customizer > Colors > Content to increase their contrast.
2. This is related to the custom code you have used to add your social icons. You would need to get assistance from the author of that code.
3. That version of jQuery is set by WordPress. You can use this plugin to load a later version:
https://en-gb.wordpress.org/plugins/jquery-updater/
Note – jQuery is being requested by other plugins on your site, updating the jQuery version may cause issues with them, check carefully after changing.
5. Your logo image is Low Resolution, upload a large version of your logo.
6. This looks like the Table of Contents plugin, the lineheight and font size of those links are too small. Check in the plugins settings to increase their font size and line height.