Edit panel not showing up (Gear -> Edit Panel -> NOTHING??)
You or one of the modules you installed is loading latest version of jQuery.  In the latest version of jQuery code like 

if (jQuery.browser.msie &amp;&amp; parseInt(jQuery.browser.version, 10) &lt; 8) {}


does not work.

This code is in one of the Drupal core files. You can find it in modules/overlay/overlay-parent.js file on line 932, 975 and 985. 

I do not recommend editing this file, but you can test this change on your localhost to make sure it is the latest version of jQuery which is causing this issue.