Charles,

I think you're out of luck on the fan part, it does have a fan motor but you have to measure RPM from the commutator current pulses. There's no direct RPM output.

It has the 8720 and 8722, but not the 8723 ... yet. Every new version (about every other month) has more chips and stuff.
You can run multiple chips simultaneously.

It doesn't have an XPort, but you can interface to an external COM port, so it could use a real XPort.

It has I2C and SPI debuggers that allow you to send anything you want to either the master or the slave. It will definitely be useful for that part.

But overall, I think you'll be better off sticking with hardware for such a large project, especially because simulating lots of analog circuitry slows it down considerably. It would probably take an 8 or 16 core computer to simulate your whole circuit anywhere near real-time.