Header/parallax images, optimization etc.

Hi CT team, Nice theme, using Rock Star Pro for a while. I have a few questions for you. Is it somehow possible to have a different header image on every page? Let's take a demo website as an example - for instance, I would like to have one image on About page and the other one on Gallery page. It would make my website more dynamic. Also, I was wondering why those parallax frontpage images (pedals and instruments) are not behaving the same on different devices. If I turn on responsive mode in browser I get that parallax scrolling effect but on few Android phones this section is completely static. Tried with different Android phones and couple of different browsers. Windows Lumia phone has parallax effect, though. And what are your recommendations on optimization, besides reducing image size, so this theme could be as fast as possible? Thanks