Spoiler
Musketeers - The musketeers of the English Civil war mainly used a matchlock musket, the length of the barrel would be around four and a half feet. This musket only had a range of around 300 yards, but it would only be accurate up to 50 yards. Seeing as it was a heavy musket it had a rest, I don't know how you would incorporate this into the game unless it was kept in an inventory slot but when you presented there was a short animation of it being placed before the gun was resting on it, this would make it take a while to fire but that could cut down on the annoying game play style of point blanking.
The ammunition would be carried by a leather bandolier that went over the shoulder and around the hip, from this there would be hung "The Twelve Apostles", these were tubes of gunpowder, seeing as you only have 12, that would indicate you have 12 shots, however the bandolier also had a flask full of power meaning you could have more shots, probably up to about 24-32.
The flintlock musket was a lot more expensive than the matchlock musket, because of this it was only really issued to sentries and the lifeguards of high ranking officers, this could possibly be some form of special unit that is "Generals Staff". Generally all musketeers carried a sword for if they ever got into some melee.
Pikemen - The pike men predominantly used used an iron head spear, mounted on a shaft made of ash wood that was between 15 and 18 feet long. Due to the fact that it was quite unwieldy, some pike men cut a few feet off their pikes, this put them at a serious disadvantage against people with a full length pike. Because of this fact there is potential for a slight chance to spawn with a shorter pike. The pike men also carried a short sword called a "tuck" for close quarter fighting.
In ideal situations the pike men would wear a helmet, breast and back plates, thigh guards (tassets) and an iron collar or gorget. These would provide some protection against things like glancing blows from a sword or pike, but a straight on attack is more than likely to go straight through the armour and kill. Much like when a bayonet kills a cuirassier in NW.
Cuirassiers - The cuirassiers are a directly evolved form of the medieval knight, they went into battle with quite a lot of armor on, with the exception of the lower leg which was covered by a long boot. They had also ditched the lance of old, and taken on weapons such as pistols carbines and swords. This would leave the player with the choice of a pistol or a short carbine, all cuirassiers would carry a sword.
Harquebusiers - The harquebusiers, like the cuirassiers carried a carbine, or a pair of pistols, and a sword. Although the officers of a harquebusier regiment would usually carry the Harquebus. They were classified as light cavalry because they wore lighter armor and rode slightly faster horses.
Dragoons - The dragoons were mounted infantrymen that rode small, fast horses so that they could move to position then fight on foot. They didn't wear any armor and they would usually carry a musket or carbine, and a sword.
Artillery - The artillery of the civil war can be separated into three different types, Siege Guns (Cannon royal, Cannon and Demi-Cannon, Heavy Field Guns (Culverin, Demi-Culverin) and Light Field Guns (Saker, Drake, Minion, Falcon, Falconet and Robinet). Most artillery was muzzle loaded, smooth bore and cast in bronze and iron.