Unlike some other cultures, there was no specific warrior class within China itself really. Here's a little bit of the history up through the Song dynasty (ending around the 13th century).

Up until the Tang dynasty, soldiers were recruited on mass via conscription. This was a large contributing factor to the fall of the previous Sui Dynasty, as wars in the region we now refer to as Korea required mass impressment of the population to fight. The war itself was so unpopular and disastrous that there was a habit of breaking one's limbs to avoid conscription (leading to the nicknames translated sometimes as "propitious paws" for broken hands and "fortuitous feet" for broken feet). This was such a large issue for so long a time, that in 642 there were Tang decrees increasing the punishment for directly self-inflected wounds to avoid conscription.

Under Tang Emperor Xuanzong, new military management and structure measures were introduced. For starts, in the 8th century, permanent military commanders were put in place instead of drawing upon aristocrats on a campaign basis. In 737, the involuntary conscription of militia forces was abolished completely. Whereas conscripts previously could only be trained, serve three years, and then be replaced by new recruits, now long standing veterans arose as the predominant makeup of the imperial army (additionally, non-chinese turkic cavalry was often employed to protect the western borders of the empire from other steppe peoples and Tibet).

The major benefit of holding such a position was that one was then immune to the imperial taxes levied upon the general populous to fund the empire and supply the income of the aristocracy, rather than being identified as a warrior class. The downside of switching to a system of permanent conscription was that guards and armies in large cities suffered from false enlistment. Some merchants and townsmen would enlist as guards, for example, and then simply pay another to take their place in duty so that they could continue doing commerce tax-free.

Pre-Qin armaments and armor for infantry mainly consisted of bronze armor and helmets, as well as crossbows, spears, and swords. As time went on, cavalry became increasingly important (as mentioned) and heavily armored horses and riders were utilized such as depicted in this terra-cotta figure along with turkic cavalry through the three kingdoms and Tang period. Moving into the Song, small amounts of gunpowder rocket weapons and bombs were also utilized.

This is still an incredibly broad question that is tough to answer in a reddit comment. However, I've been doing research on funerary military figurines for the catalog of an upcoming exhibit on Chinese art at my university's gallery, so I can point you to the scholars and sources I found most interesting/useful.

• Warfare in China to 1600, edited by Peter Lorge, is a great collection of articles on various topics. I'm not sure exactly what time you're interested in, as "knights"/"samurai," and "ancient" don't usually do together, but this book provides something during each dynasty for most of Chinese history.

• A Study of Early Chinese Armor by Albert Dien is one of his more oft cited works and a comprehensive discussion of the development of Chinese armor from before the Han dynasty to the Ming dynasty. Its illustrations are plentiful but somewhat small, though I found images of the actual sculpture, relief, or artifact they were referencing were easy to find online. I'd recommend any other texts by Dien. His most comprehensive is Six Dynasties Civilization, one of the more comprehensive books on the period.

• Medieval Chinese Warfare 300-900 by David Graff picks up where Dien's works leave off. He takes a more historical approach than Dien, who focuses mostly on material culture.

• This piece from Edward Dreyer discusses the life of a great Han Dynasty general and touches on number of things you may be interested in: civil-military relations, tactics on the frontiers, and military organization.

This is such a tough question as it'd be like asking "how were the European soldiers armed historically"...the scope of time and variety are immense.

I'll focus on broad strokes and if you want to ask questions later on specifics I can give more detailed answers with sources if I know if it:

Pre-Eastern Han Dynasty: the government structure of Pre-Eastern Han Dynasty (so basically think 220 BC - 10 AD) was technically imperial but still has a lot of hold-overs from the pre-Imperial era of China where China was a confederation of kingdoms & states. So what this means is powerful client kingdoms to the Emperors - generally members of the Imperial clan or other nobility, maintaining armies for themselves. So the system was some kind of hybrid between feudal and Imperial.

There was no dedicated warrior class, but there was mass conscription. In terms of warfare & technology - we know that mounted archers & crossbowmen (who seemed to act like dragoons almost) were used a lot. Compared to the size of the Empire there were not that many professional Imperial armies, instead vast militia armies would be raised and drilled (a lot of these men would have served under the one year of conscription) by these powerful princes and dukes across the land.

During this period the Chinese scored a series of impressive victories, most notably the Han-Xiongnu war where the Xiongnu confederation was essentially destroyed. And they maintained their Empire surprisingly well against frequent revolts/incursions by what were more martial and pastoral people like the Qiang, Xianbei, Wuhuan etc. (I mean, not making any grand theory but generally pastoral cultures can conquer agricultural cultures).