after loading a webpage on my laptop, does the website continue to use data while its on my screen? Or does it only use data when it is loading a page in or when I move from page to page?
Some web sites will, some web sites wont. It all depends on how the site was written. Some will automatically refresh content (either partially or fully). Some will preload content trying to anticipate your next move, while some will preload videos in the background hoping you'll click to play them.