We all work for bad leaders from time to time. In some cases we have to be humble and let those in charge be in charge. On the other hand if the NCO is being abusive in dealing with his subordinates you might want to consider requesting an investigation into his actions.
Before you proceed you may want to look at this issue from the Platoon Sergeant’s Perspective. Is he just a hard, aggressive leader? Is he learning to be a leader? Are his actions really wrong or do they just rub you the wrong way? Once you have evaluated these things and honestly believe there is an issue then you have an ethical decision to make. When you step forward to make your claims you better make sure you have your stuff together or you could face some serious consequences.
You do not want your actions to be seen as mutinous or seditious which could put you in a lot of hot water. Once you have sat down and written out a document that presents the facts in a clam, unemotional, and professional manner, come up with a series of solutions that could resolve the issue. Once this is complete consider going to the JAG or IG to get an azimuth check. Make it known to them that you do not want them to do anything you simply want advice on how to handle the issue and to see if your claims have merit. Once you have a disinterested opinion on the matter you can then decide whether to let the issue go or proceed. If you choose to proceed I would start with the 1SG and Commander. Most Command Teams want to do what is right and will not tolerate abuse or poor leadership.
Based on the information you provided most of the issues seem to be a personal objection on how the Platoon Sergeant handles things. Therefore I would caution you to ensure anything you take forward to the chain of command should be specific in nature. I would also encourage you not to bad mouth the Platoon Sergeant around subordinates or attempt to get them to side with your views as this will only be more destructive. Before you do anything I would encourage you to have a professional one on one discussion with the Platoon Sergeant. Set the tone that you are a team and you want to support him and make him and the platoon look good but you need some assistance from him. Make him part of the solution not the problem. If this fails then proceed how you believe appropriate.