im kind of new to cockers but i know a little about what your asking, a ball detent is a device screwed into the side of an autococker, you can also see it inside by looking through your feed neck and pulling the bolt back you will see a little ball, the purpose of that is to stop double feeding (firing two balls at once), bolts are what hit your ball when its loaded in the breech, if you didnt have a bolt and you pulled the trigger the ball wouldnt shoot, a aftermarket bolt will help by increasing rate of fire and by is uses less gas, and if you short stroke there is less chance of the ball breaking. again im not sure my explanations are totaly accurate but it gives you and idea.
Bolts dont affect your accuracy. Your accuracy depends mostly on your pain to barrel match.
A new bolt will most likely be lighter and have better flow. The lighter bolts are supposed to help your cocker be able to cycle faster becasue of the reduced weight, and higher air flow means less pressure needed to operate the gun.