Error code P1221 and related questions

[Bushbasher]

I just scanned the wagon and got error P1221 and now I'm a little worried but also a little confused. Forscan says it may be a faulty or damaged PCM or a short to power or ground in the VSS or a VSS open circuit. I checked the PCM to see if there was any moisture getting to it but it all looks A ok so I've ruled out external damage to the PCM. So I have a few questions....

1) Can there be a short or open circuit in the VSS if the speedo is still working correctly?
2) If so, what's the easiest way to get at the VSS module? From under the car or through the shifter hole from inside the car?
3) Is there any other obvious point in the wiring loom that would cause a short in the VSS circuit?
4) Is the VSS in any way linked to the engine operation directly that could affect fuel mileage as that's what prompted me to go looking for faults in the first place?

Any help on any of the questions would be greatly appreciated.

Cheers
Bushbasher