Hi Roger,
I have solved the speedbrake issue to my satisfaction by editing the [airplane_geometry] section in the Aircraft.cfg as follows:
spoiler_limit = 50
aileron_to_spoileron_gain = 0 //1
spoiler_handle_available = 1
min_ailerons_for_spoilerons = 0 //9
min_flaps_for_spoilerons = 0.000
spoilerons_available = 0 //1
auto_spoiler_available=0
spoiler_extension_time=1.000000
In FSX I could get the S/B to operate with the "/" key but they also operated when full aileron was applied.
Now they operate with the "/" or the S/B switch in the cockpit or the throttle quadrant lever, but not with the ailerons! However, for the "/" key to operate, the S/B switch on the throttle must be set to the neutral (central) position.
I don't understand why your AIRCRAFT.CFG had those wrong settings. The AIRCRAFT.CFG I'm using already has the same settings than your edited version (except for the extension time).
Perhaps you got a corrupted file

Cheers,
Hansi