You're spot on about Shane. It was Rick he was smashing up. Andrea tells Ed they know about what he does they seen the bruises etc so he's beating Carol for months at the camp and Shane did damn all. He probably just looked the other way unless Ed did something to endanger the camp like lighting a fire too high etc. He only threatened Ed after cos it had to look legit that it was about Ed and not something else

exactly, I saw someone talking about their favorite thing about Shane was how he respected and cared for Carol and used him defending her from Ed as an example but that's not the case AT ALL the only reason he hit Ed was simply because it was the only scenario he could rightly beat someone to a pulp without it being a problem and it made him look good, especially in front of Lori otherwise he would have turned a blind eye just like he always had