On the quiver part, I will go on:
According to Wikipedia:
Back quivers are secured to the archer's back via straps, with the nock ends protruding above the dominant hand's shoulder. Arrows can drawn over the shoulder rapidly by the nock. This style of quiver was used by Native American tribes of North America and tribes in Africa. The Japanese Samurai, also used quivers on their backs, called Yebira, while both on foot and horseback. While popular in cinema and art for depictions of medieval European characters (such as Robin Hood), this style of quiver was never used in medieval Europe. The Bayeux Tapestry shows that most bowmen in medieval Europe used belt quivers.
Source: Osprey books.
The most common style of quiver is a flat or cylindrical container suspended from the belt. They are found across many cultures from North American to China. Many variations of this type exist, such as being canted forwards or backwards, and being carried on the dominant hand side, off-hand side, or the small of the back. Some variants enclose almost the entire arrow, while minimalist "pocket quivers" consist of little more than a small stiff pouch that only covers the first few inches.
So the style we see in Bannerlord actually reffers to tribal warriors from Africa, the Japanese samurai and American natives.