Here's the primary point, with cameras just as with RC equipment, buy the best you can afford. It will give you better results and last longer.

The DSLR Canon can do anything you want. The standard zoom is fine for most of your use, telephoto lenses certainly work better for flying photos. Take your photos at the highest resolution you can, this will allow the cropping with minimal loss of quality.

Now for my slightly of topic mini rant, TURN OFf AUTO FOCUS WHEN SHOOTING VIDEO OF MOVING OBJECTS!!! It can never keep up. Set focus to infinity. This is also true for shooting with telephotos of moving aircraft.

I've been using Canon cameras for the last 20 years and am what may be their biggest fanboy, so take anything I say with a small grain of salt.

Good luck shooting