Is trivial to mild mitral regurgitation usually audible to a cardio with a stethoscope? is this something that normally progresses?

Mitral regurgitation: Audible sound depends on amount of turbulence caused by a lesion. Generally trivial MR causes little or no murmur, mild MR might cause some. The minimal MR lesions usually don't progress unless endocarditis occurs but progression is not impossible.

Depends: Depends on the severity and how well trained the air is. Progression depends on the etiology. A lot of people have mild regurigitation that's physiologic. However if it is due to mitral valve prolapse that could progress.