I modified CSS for Page title, now it’s scaling on all screen widths. On low resolutions, image is repeating. This is result of responsivness you want so you should upload image with even bigger height to cover the space on low resolutions.
Regarding Revolution slider, this is normal slider behaviour. Slider is scaling images to fit into the container otherwise you will have same problem like on page title, image won’t cover whole container.
You can see that it’s same in our live preview.
Problem with images you use is that they have text which you want to be visible on all resolutions but because slider is calculating width/height, text goes out of viewport. I suggest that you add text as layers, and slider will position text so it’s always visible. You can also ask Revolution slider authors if they have some tricks to fit background better:
Regarding last question, for page title, use CSS below to hide it:
This CSS is specific for About us page. If you want to hide on other pages, copy/paste is and replace page id.