Is a 3 speed wiper transmission teh same as a 2 speed?

The "transmission" is part of the wiper motor so yeah they are different. The connecting linkage is specific for 3 speed as well. Yes, pull it all.
One thing im not sure about is the dash wiring. Im not sure if you can just plug in the 3 spd switch on your existing harness. Never looked into it that far.....just something else to consider / research.