It has been a LONG time since I've used LRTimelapse.  The previous version on my computer was 1.9.x.  

In previous versions, LRT would interpret the luminance differences, calculate the adjustment factors, then write those adjustment factors into the metadata (if I recall).  Will it still do that?  I realise the newest version is a more end-to-end timelapse creation workflow application; however, for now, I'd still like to do the bulk of the work in Lightroom and just use LRT for the deflicker functionality.

Thank you.

Yes, it still does. But everything is more transparent now. The adjustments of the Holy Grail Wizard and the deflickering will be made on background layers, so that you are still able to use alle the regular tools for your keyframe editing.
Please make sure to watch my tutorial videos to learn about the new workflow: http://lrtimelapse.com/tutorial

Thanks, Gunther. I've been watching the workflow video this morning.

In terms of workflow, I'm converting to b&w then masking in colour in a specific area over time. I'm thinking then that I'd be best to do all of the keyframing, editing of keyframes (exposure, brightness, etc, convert to b&w) then do the deflickering in LRT and finally come back to LR and do the masking in of colour before rendering out the final video. Yes?

Also, it's still possible to use the regular export function in LR, bypassing the LRT export, then import the rendered files directly into Premier or AE, right?

You could do the color keying in the first pass too - just make sure to not using the B+W tab for the conversion, but to reduce the saturation.

Of course you can export from LR as you wish and render in Premiere. But you could as well use LRTExport and then pass the intermediary sequences into Premiere or AE - then you'd already have subsequent file names etc... Or use LRT to render a lores preview and later bring the intermediary sequences into Premiere - as you wish.

In practical use I mostly render Prores with LRTimelapse and bring this into Premiere Pro because the performance is much better when editing Prores files then image sequences. And the quality is the same.

I've used the Adjustment Brush to apply a mask then reduce Saturation on the mask.  That way I can go back in and use the Erase function on the brush to bring back in the colour where I want it.  

I only bought the Private license, so ProRes isn't an option.  I'm old.  I'm used to bringing image sequences into Premier, or AE, or Sony Vegas.  Learning new tricks isn't something I'm good at.  :-)

All good - I was just outlining the options.