I have friends who swear by token systems (stars, tickets, etc.) never been a huge fan myself, the kids start to respond to the incentive more than the behavior. But your mileage may vary.

Hitting is hard. It’s very developmentally appropriate but emotionally charged. I do not mind being hit, but my wife absolutely cannot take being hit by our kids (understandably!). Sometimes she has to remove herself from the situation because her response is (again, understandably) emotional. I find that my kids need to be told what the right behavior is in that moment - to them hitting isn’t necessarily as weighty or impactful as it is to an adult. It’s just a way the feel to express their emotions, and I see it as my job to teach them other, better ways instead