1) We have updated theme to latest version and don’t see any problems with the additional information tab. So, probably you made some changes in template files that caused this issue.
3) You have a lot of variations. We would recommend you to disable variation swatches on grid http://prntscr.com/pdi8zv it will reduce the number of requests for pages where you display products and speed up the site. Also, we have installed cache plugin.
