Users don't care about the processors and developers don't want to care. This stuff will work on all of these devices unchanged. While Linux didn't help much in that area, it did provide an easier way to get Kaffe running on the devices of interest. It saved us a lot of man hours to get up and running. But with all this abstraction of applications in XML and Java, multimedia could potentially suffer.
Graphics applications are always happier when they're closer to the hardware.
You can structure it as shared library or a separate entity. The video demonstration we have is done like that. It's a completely separate process. We just say 'here is your screen space, now draw to it however you like'. While Wilkinson doesn't want to take Kaffe to other platforms, it would be possible.