I don't play at a great level so for me walking is just part of what I think you should do. I can understand at higher levels when someone is being paid, ethics aren't as important to all players.
If I think a player has hit it and he doesn't walk I just ask them politely if they did. If they say they didn't I'll give them the benefit, sometimes your eyes and ears play tricks. If they admit to it, then they are happy for the umpire to be the sole judge and therefore I will appeal for anything I think he might give. I don't appeal unless I think it is close to being out lbw otherwise. I'll also apologise to a batsman if I appeal and I realise I have got it wrong.
Sledging is generally pretty boring and again, at my level, not acceptable in my opinion. I find it odd that you'd want to be rude to someone, usually who you don't know. The few times I get people commenting on my technique (no-one in my league has a decent technique) or other petty jibes, it has only served to focus me more and generally I bat better.
Some idiot the other day started moaning at me for re-attaching my thigh-guard strap after it came loose running a single. I hadn't yet faced a ball, we were clearly going to lose the game, what did he gain apart from me now thinking he is a (insert your own word).