possible mating behaviour

So my questions are this: 1: why Is my cockerel (6 months old) pecking the back of (only) one of my pullet’s head & back? 2: when will he calm down? 3: can I get him cartrated? If so, will it kill him? 4: what can I give to my pullet & cockerel flock as a treat every now & then 5: my ??? X...