Wordpress site adjustments & optimization for loading

Our website is fully designed and developed. There are just two minor tweaks I need made, but the bulk of this work will be in optimizing the page loading. Minor Updates: -Update template so that image captions can only be shown under images in the body of posts. (see screengrab) -Find a balance so Super Cache is not preventing Twitter feed from updating -Make twitter share button use short URL Bult of the Project: We have fairly decent page load grades (see attached gtmetrix report). However there have been issues with loading in large shared networks. I am looking for an EXPERT in WordPress to run through an existing website and fix any security issues, errors and improve loading time. To do list includes; Create faster load times - MOST IMPORTANT Add Expires Headers Optimize images - possibly move to cookie free domain Combine stylesheets Defer parsing of javascripts This is a general list, all may not be necessary as some steps have already been taken to optimize loading, and I might be missing things you can do, you tell me. In addition your recommendations for best practices going forward. We would like to get our load time down to 2 seconds or less, so looking for an expert in this area. Looking to have this done as soon as possible. IMPORTANT - If your website examples do not get excellent performance reports using [login to view URL] do not apply. Thank You -This site is live, so if it needs to be down, I would prefer you use maintenance mode and that happens at night US time If this goes well may have more work for you in the future