AS far as shoulder pain it can be avoided by benching correctly. In proper position you should actually have you foot placement on your toes not flat, legs squeezing the bench holding you in position, butt on bench,work on flexability and get as much arch as possible and the weight should be on your neck and traps, ELBOWS IN, this is key in benching and saving your shoulders,grip the bar as wide as possible,this cuts down the distance the weight has to travel. Bar travel should be in a straight line,its all about proper form, leverage,and how to apply it. I hear all the time people saying when you get stuck to arch the bar back over your shoulders, which it naturally wants to do because because most peoples shoulders are stronger than their triceps, this and not keeping your shoulders tucked in will ruin your shoulders and you will not be benching for long, if you want to bench alot of weight for a long time you need to really focus on tricep strength 1st,then shoulder.