If you're bored, here's a really extensive list of different types of animals' weights and their organ weights: https://dspace.lib.ohio-state.edu/dspace/bitstream/handle/1811/3110/V40N05_219.pdf?sequence=1
Yes. A large man's internal organs will be larger than a small woman's all things being equal. For instance a female brain weighs (if I remember correctly) 100gms less than a mans. (Source: "The Female Brain" by an author whose last name I can never remember the spelling of)
Agree with Nance, fat is stored not only under the skin (above muscle) but also around the organs. So individual size, I am not sure, but the entire internal organ system composition would be larger given the fat surrounding.