How is Kenny a coward? Saving Duck was something he just did as his dad but saving Shawn would've made him a hero...not everyone is a hero. Are you guys saying that you wouldn't hesitate to run over and try to save someone you hardly know when there are zombies that could get you too? Also, considering the fact that he hasn't had enough experience to get used to the zombies, he wouldn't have been ready to just jump in and save the day. Lee is a hero, he did something that would've caused a lot of people to hesitate. If it was my best friend, I would jump in to try and save her...but if it was a stranger I'd probably hesitate and not out of being a coward.
Kenny was right to 'kill' Larry after he died; the chance of Larry becoming a walker was too much of a risk to take. Yes, it was harsh, but you will always get someone like that. Kenny is realistic, he does what needs to be done to survive and you can't really hate him for that. For all you know Larry could've become a walker and killed everyone right then.