Hey Adam - The scripts Google Pagespeed insights mentions are default CSS and JS that is essential to your page in functioning and displaying properly.
As for the fixed header script - It's best placed 'before body end tag', but regardless the script only works after the pages elements are loaded. So it's not render blocking your page or causing additional load time. All it's doing is applying a small amount of CSS changes to your box element.
In general I wouldn't rely on Pagespeed insights as tool for improving adwords quality score. Pagespeed insights is suggestions to improve page speeds, while Adwords landing page quality has more to do with content and relevance.