I'm thinking of venturing into the realms of RAW format. A quick question on chromatic aberrations.

I know that it is possible to correct for chromatic aberrations if your photos are taken in RAW format... But how does it work?
1) After correcting for the aberrations, does the image suffer a drop in quality?
2) Why is it we can correct chromatic aberrations in RAW format but not jpeg format?

Thanks in advance!