Given the observed 'red shift' of distant galaxies indicates they are accelerating away from us, how much further away are they now?

Red shift is an indicator of velocity, not acceleration. Used in conjunction with a standard candle (Type Ia supernovae) it's possible to determine that the universal expansion is accelerating - Cepheids are too close for that. For the more distant galaxies it's wrong to think of the red shift as simply a doppler effect - you need to factor in things like the density of the universe.

Essentially, I'm asking if the red shift has been conclusively proven to be a Doppler effect.

Presumably the level of red shift allows accurate calculations to be made about the rate of acceleration. Do these correlate with measures of the change in distance, as provided by (for example) changes in the apparent brightness of Cepheid variable stars?

I suppose, in terms of timescale, it might make sense to use the first point at which both the red shift and distance were being accurately measured (though I'm not sure when that was . . .)

We can know till the red-shift corresponds to the speed of Light. Beyond that we can't see as the light coming from there can't overcome the recession speed that is also the speed of Light.

Now compared to when?