The speed wire is in the harness. Now, for the reverse issue: Unless you are actually installing a backup camera, what most shops do is forget about the reverse wire, and twist the e-brake wires together, so that the Nav unit thinks it always has the e-brake on. The advantage here is that now you (or for legal advice, your passenger
) can operate the Nav while the car is in motion, otherwise you'll have to pull over anytime you want to put in an address, etc. Like most things in this country, the switch is there for liability.
Drop me a PM if you need detail specifics on any of this.
Patrick