Sorry I haven’t replied - I’ve been busy migrating as many systems as I can from RedHat to Debian after the latest braindead moves. It’s taking a bit longer than anticipated 
The nightly builds expect that the BLTouch is connected to the 5 pin socket on the mainboard.
A key giveaway that the wiring is wrong is if the probe does multiple deploy / stow cycles. There is a general BLTouch FAQ that hopefully helps with the most common problems.
As for Z movement, most of my builds will not allow a negative Z movement until the printer is homed. This is a protection mechanism to try and prevent people from accidentally driving their nozzle into the bed (as we’ve all done).
You should be able to move down to Z=0 after homing the printer.