I'd like to read trackpad multitouch gesture and coordinate data into my C++ program. Where can I find some introductory tutorials on doing this?
The way to go is indeed objective-c++, which is just a mix of c++ and objective-c. It's very powerful because you can start using all the Apple frameworks in your C++ projects.
You should learn a bit of objective-c, rename some .m files to .mm (or .cpp files to .mm) and read through the apple documentation on touch events. ( https://developer.apple.com/library/mac/documentation/Cocoa/Reference/ApplicationKit/Classes/NSResponder_Class/Reference/Reference.html#//apple_ref/occ/instm/NSResponder/touchesBeganWithEvent: )
Or if objective-c scares you, check out this multitouch trackpad addon for OpenFrameworks https://github.com/jens-a-e/ofxMultiTouchPad