Well, you don’t need the relay board, the existing torch relay works just fine, you just need to add a 5V power supply to isolate and repower the 5V for the relay and THC interface. You can also roll your own Z Axis using Open Builds tracks and wheels. See Finally completed my CrossFire mods - #11 by TomWS and an earlier post that talks about the Z Axis mod.
And, Yes, I agree, this thread is a VERY good source of information.