RAW is unprocessed sensor data from the camera. My camera is 8MP and a RAW file is about 10MB. A high quality JPEG is about 3.5MB, and is the result of processing in the camera. Using RAW data would give the same starting point. As far as I know, you still need to post process the RAW file.

I usually save to JPEG. I normally shoot in natural light. I believe you can get a more grainy appearance with a faster ASA setting. I see that if I am shooting in low light and try to increase the brightness.

If you save to a more lossy compression ratio, you would lose image quality. I din't know how far you can go on compression. You might try a save to a lossless compression.

Rich