The club thing, I assume, is just some testosterone/dominance thing. They're not actually looking for a fight, they're just looking to establish dominance over the other males in the room. I don't really have any advice on that -- depends on (a) how tough you are, and more importantly (b) how much you care about that stuff.
As for the sidewalk thing, this drives me absolutely nuts. When I'm walking, my policy is a little less aggressive than some of the other posters: I just pause momentarily right before impact, and brace my shoulder. That way I'm not even moving, so it's completely their fault for walking into me, but they definitely get a jolt. And often once I stop they'll make a last-minute move to get around me, because once I've stopped it's clear I'm not going to dive out of their way (which shows that they were actually paying attention and simply assumed I'd give way).
And just to clarify, this is always on the assumption that I'm only taking up half the sidewalk or less. If I'm hiking on a narrow trail where one person will inevitably have to give way, I'm more than happy to step aside.
With running, I obviously can't be bothered to stop, so I don't waste my time trying to "teach lessons" and just try to dodge people as best I can.