IQ of Panasonic 14-45 f3.5-5.6 vs. Panasonic 12-35 f2.8

This isn't true. Not everything thinks this, because it's clearly wrong. You can clean up CA starting with any format, include JPEG. But every time you save back to JPEG, you lose detail. With RAW, you never lose what the camera first captured. Even saving in lossless formats, you only have what was in the image as you saw it on your monitor. But repeated savings to a lossless format without changing anything will not degrade what you first saved. This isn't true for JPEG.

--
Frank Paris