As for how I mentally store information -- well, too often I guess I kinda don't
...but when it's working, it's sort of vaguely diagrammatic, but not exactly visual (usually). I do know that I have a hard time remembering anything unless I understand how it fits in with my general understanding of the world -- I need to get the underlying concept; I can't just rote-memorize stuff (without a lot of work, anyway... (autist t-shirt idea: "Ask me about pi!")) unless it's something I've heard over and over again and I enjoy it enough to pay attention (hence playing music by ear and also reciting Monty Python, The Goon Show, and Douglas Adams at the drop of a hat).