It all depends on what you're shooting, and what you want your final result to be. There is no hard and fast rules. As far as the 50mm - it really depends which one you're talking about, the 50mm "macro" is not a true macro lens and while I've had no personal experience with the lens I've heard many say you're much better off getting one of the true macro lenses. If you're talking about the 50mm f/1.8 or 50mm f/1.4, both are great buys 
. To use them for macro you'll have to pick up some extension tubes (kenko sells a set for ~$170), but with tubes they aren't that bad of "macro" lenses. Certainly something that'll let you learn and experiment with macro until (and you will!) you buy a true macro lens (Canon 100mm f/2.8 macro, Canon 60mm EF-S macro, etc.).
That's what is commonly referred to as the "kit" lens. It actually isn't that bad of lens - it won't be anything close to a macro lens, or the higher priced normal range zooms, but provided you learn what its strengths and weaknesses are it isn't a bad lens to start out with. And if you slap some extension tubes on the thing it can actually do some not half bad macro.. The kit lens can crank out some remarkably good pictures - IF the photographer learns how to use it correctly. If the photographer doesn't learn how to use any lens/camera correctly it doesn't matter if its $5,000 L glass - it'll still make shotty results.
If your 18-55 is the IS version, then that seems to be a decent lens (though I have never owned it). If you are getting the non-IS version, I recommend you just buy the body and a different lens (I wish I did).
I was going to say the same thing. I got a 100 mm macro and it takes the best closeup pics!
