You don't need a pro camera to take good shots, just practice.
I think you managed to get good exposures even with the direct sunlight, which can be tough. I would recommend shooting at their eye level, like in the first one, and using a longer lens (more telephoto) when shooting portraits.
I prefer the first one, actually. The second one rubs me the wrong way; I guess I can't get past the rule to crouch down so you're not looking down on kids.
I don't use b&w, so it's intresting that I like it better than #3.