Oh, so sorry we forgot the doxygen comment of CCSet. I created issue #709, it will be done in this version. Before we finish this issue, please refer to tests/tests/Box2DTest/Box2dTest.cpp, in line 175, Box2DTestLayer::ccTouchesEnded(CCSet**, CCEvent**). This functions shows how to traverse the objects in CCSet.
About CGPath, you can refer to CocosDenshion/iphone/SimpleAudioEngine.mm, this file shows how to call objc interfaces in cpp class. By apple’s rule, you can mix objc & cpp source in files with .mm subfix.