Cameras
It really does not matter, what camera brand You use, be it Canon, Nikon or one of the others. There's no big difference between them as far as the quality of the results is concerned. A DSLR is still a must have, I think. May the smaller cameras get better and better, they still do not produce results as good as DSLRs do. This is mainly due to the smaller sensors used in those cameras, which do produce more visible noise on the photos. This can be corrected with adaequate software, but not without loss of small details.
Good reviews on Cameras can be found here:
Even more important than the Camera body is sthe lensed attached to it. As - at most airports - we are quite far away from the action, a telelens is necessary.
Tests and reviews can be found here: Photozone