Shifting
I know how you feel. Mine sat for a year while I tried to figure out what to do for shifting. I even tried to buy one with no response from the vendor.
Good Luck.
Controller
I used an Omron Zen PLC to control my A340. All the info you have so far is right on track. I mounted the switch buttons on my steering wheel also. I have since change over to my Rail Shifter. See my website. Also there is info on finding out what wire is for what.
Good luck