1) Again- whole system, the beautiful OCS chipsetand its strong integration into the whole computer. The closest thing would be an Atari, but they came out a few months later, and really the Amiga had better gfx/audio/OS...
2) Motorola DO make the 'Coldfire' (now coldfusion?) line of processors which are somewhat 68K compatible, they seemd to be based on 68K at the least. There are independent developers making a coldfire accelerator for both the amiga and atari, classic macs lack that kind of serious interest.
3) Macs generally couldn't do the multimedia of the amiga. Amiga's also were first desktops with Broadcast quality Video (ever seen those M&M guys?)
