Wonderful pictures Marcel.
Regarding a lens, my first Nikon DSLR came with a Nikon 18 - 55 mm lens, and a Sigma 70 - 300mm lens (with macro) at f4 - f5.6, and image stabilisation.
I found it a touch too slow, in auto-focus, for most airshow work, although overall it performed reasonably, so I now use a Nikon 50 - 300mm lens on my other Nikon body.
But for general use, and considering the low price (around £85 to £95 in the UK), it was very good, with minimal 'fall off' at the frame extremities, no noticeable 'noise' in normal use, and nice, clear, sharp images.
Pity your camera is Canon, otherwise you could have the Sigma lens from me !