Answer :

Question : What was a Knight ?

 answer : a Knight was a solider who fought for their Nobles 

Question : why did Vassals have to serve lords ?

 answer : A vassal is a person who receives land and protection from a lord in return for loyalty in other words Vassals had to serve lords cause since they got land and protection they have to serve the Lord

Question : what was a typical manor like ?

answer : a typical Manor includes the house of the Lord , which the lord of the manor lived with his family in a large house that was often built of stone . They a  lived comfortable and leisurely life compared with the serfs . Among other things they hosted large dinners consisting of many meats , Serfs : Most serfs lived in a small damp huts made out of wood and mud . The ground often served as the floor . Each hut usually had only 1 bed , which was made of piles of leaves or straw . Families sis their cooking in the hut over a fire on the floor Most peasants survived on a simple Vegetable stew and stale bread .

HOPE I HELPED YOU :P