Fourth Wing

This is a very good book but i an also thoroughly confused about everything thats going on:

Why is it accepted to kill random cadets throughout the year? Why do the dragons attack the gryphons if theyre not the real enemy? Don't the dragons know this? What was the first revolution where Xaden and his buddies got those marks for? Why do the dragons even care for their riders? Where is the bonding? Suddenly they love Violet and Violet loves them and even though her and her dragons have more bonding than anyone else its still kinda unbelievable that the dragons in general would go through fire for a random human within a short timespan. As a matter of fact, WHEN did Violet suddenly become friends with Ridoc and Sawyer? It was never shown but suddenly they were friends.