1) Sorry but I can't locate how to get back to the step 19 area
Try going back to Step 11. Of course, instead of creating a new Lamda function, just click your existing function and it will take you directly to the code editor and environment variables page.
2) I refer to the "var" in red before the variables. I did see the image you posted.
Once you're on the correct web page, I think it will make more sense. Environment variables are not added to the code in the script editor. You add them lower down on that web page. In the first video James made, at about 13 minutes and 20 seconds, he says "We don't need environment variables..." and his mouse cursor indicates that part of the page.
Now, however, you
do want to edit the environment variable fields so that they look as James posted in his screenshot.
3) With reference to step 6, would that new group provide the info necessary to issue the commands as per video.
It depends what you mean. In terms of how VC is interacting with Alexa, absolutely. All the steps of the instructions must be followed.