Some were, most were ordinary people.
Twitter wars.
serfs, knights and nobles
grundies and looking after king
Manors
During the middle ages, knights were expected to be chivalrous and truthful. they were to serve and protect the people, the monarch and the country.
The muslims and crusaders fought against each other in the middle ages during the crusades.
received salaries in payment for their service
in the middle ages there were rich and poor knights
There were monastic orders of men who took such vows. They included the Knights Templar, Knights Hospitaller, and Teutonic Knights, and possibly others. The crusaders were rather like this also, but they were not necessarily under vows. There are links below.
knights
protect the kingdom
No, people only invented religion after the Middle Ages. (Sarcasm)