iOS exploitation... there was a talk somewhere about that. It was a "PowerPoint." I believe it was about the kernel, but it was iOS 2.1.
arm-elf-gcc... if you Google (or Bing, or DuckDuckGo, etc) it, you can find a package for Mac. Also MacPorts happens to have it. Windows, one solution is to use Cygwin and grab a Linux package. Third option: multi-boot / VM.