some basic questions about muscles

Hi guys
1 - as we know , when we practice , satellite cells join to the injured muscles for hypertrophy
But as all of us know , no one can have for example 50cm biceps diameter and there us an end point(according to genetic and etc) , i want to know what physiological process happened that no more exercise can cause hypertrophy in muscles?
2 - i heared that todays , stretch does not apply for muscle trigger point and spasm and the new approch is approxiamtion , is it true?according to what evidence?
3 - if we do noe use a muscle , is it possible that it disappear forever?if the answer is no please explain exactlly what physiologicall process prevent that?
Thanks

Some of it is true but stretches do help treat muscle trigger point.