That form of combat is called "Jousting"
Knights who demonstrated their fighting skills in contests were often called tournament knights. Tournaments were events where knights competed against each other in various combat activities to showcase their prowess and skill.
It was called a Tourney. The early tourneys were more of a battle rather than the jousts of later period, the aim of the tourney was to literally take people hostage and thus you would earn money off the ransom. Strangley the practise of a large battle diminished towards the end of the medieval era; but the peace talks between Henry viii of England and the french king were held with a old style tourney which are still seen as Battle-honours for some of the older regiments of the british army.
Yes, medieval knights did receive education, typically starting at a young age with training in various skills like combat, horsemanship, and chivalry. They would also often learn reading, writing, and mathematics, although formal education varied depending on wealth and social status.
Most often the term would be a Tournament or a Tourney, however For most of the middle ages the Joust with lances was only a sideshow for the main massed melee and at some points activley disallowed since the partcipants became too tired for the main event. Later on the joust became more popular since the martial aspects of the sport became less pronounced, much like the way sport-fencing has overtaken true fencing.
received salaries in payment for their service
A formal declaration of war.
There is no formal minimum requirement, although a high combat level is recommended, since it is primarily combat-based.
Differene of formal,informal and non-formal education
Mental health/combat stress control personnel.
difference between formal organization structure and informal organization structure.
formal and informal rhythm
A formal agreement between two or more nations is called a treaty.