Since this has round balusters, will the top and bottom rail have round holes? Also, what is offered to stop the rattling noise from the balusters?

Thank you for your interest in our products! The holes in the top and bottom rails are round to fit the balusters. To keep the balusters from rattling, make sure to make the railing section snug so they fit tight into the rails. Kindly-Trex Customer Care