1) A squad of nine people is just too big. The U.S. is concentrated on small, highly trained squads. While the Chinese have bigger squads but with less accuracy.
2) I don't really see the use of having both Marines and Rifleman in one barrack. If their only difference is accuracy and range, I don't really see the use of it.
3) There already are alot of strikes so far, so its better to have just a recon UAV. (there is no shortage of firepower)
4) It's better to have it as an ability. A .50 cal sniper is mainly for soft skin/ lightly armoured vehicles. There already are good anti infantry sniper rifles (Accuracy International Arctic Warfare sniper rifle)
Oh, and welcome to the forums.