Mesa 7i96 bit file location for dropdown, StepGen 4 Dir+/- mapping

While waiting for the SpinX1 to come back in stock (anyone have a spare?), I thought I'd use my shiny new oscilloscope (a Christmas present, thanks Mrs F.) to setup/check the pwm output from my 7i96. Although I'm not exactly confident in what I'm doing, I now have a pwm output from the Step4 Step+/- terminals and a ramp up of spindle speed as per here: linuxcnc.org/docs/html/examples/spindle.html - minus the 'spindle-at-speed'.

The next steps were to use the Step4 Dir+/- to control spindle CCW and connect up the single pulse spindle encoder for the 'at speed' pin as per forum.linuxcnc.org/38-general-linuxcnc-q...e-emulate-an-encoder (I think...?).

When I go into PncConf, I cannot select the '7i96d_1pwm' bit file from the dropdown - is there a specific directory I have to place the bit files (I tried /lib/firmware/fm2) or a config I need to update. Or indeed, do I need it at all?

Also, the 'Num of pwm generators' always reverts back to 0 (zero, instead of 1). I can manually update num_pwmgens=1 in the hal file but keep forgetting!

With the 4 StepGens and a spindle encoder configured, I now have two GPIOs(?) 025 and 026 showing - are these Step4 Dir+/-? Can I use one of these for spindle enable and the other for spindle CCW? Connected back to gnd or +5v? (I currently have the SSRs configured to do this, but it would be good to free them up).

Quick edit: forgot to mention I'm on v2.8.4.