Adaptive Image is great for loading a smaller version of the images on smaller devices. It determines breakpoints, or you can set them, and saves an image into different sizes. Then automatically loads smaller images on smaller screen sizes.
For hiding content, you need to decide if you want the website to be adaptive or responsive. If you are hiding block regions on a tablet view (<768px), and someone who had their window size reduced makes their browser window full screen on a desktop, are they suddenly going to be missing blocks and regions?
I tend to just use CSS media queries, and re-arrange the content on smaller devices, and If I really have to, then hide content with display:none when the browser window, or device screen size gets reduced to a certain width.