I am not sure about your second question (not clear to me). But, I can help you with the coupler replacement.
The coupler is not replaced from the bottom. You need to remove the cabinet from the washer. This is easy.
First, lift the console. Behind the console you will find two large gold colored clips that hold the cabinet at the left and right sides under the console. Remove those clips. Now the cabinet will come off the frame of the washer. Next, remove the pump from the motor, then remove the motor. There you are! The coupler is right there.
You do not need to remove the transmission.
Matt