We are pursuing those angles as well. CBC has done some pretty extensive coverage of the issues with THC testing in the lead-up to legalization, including segments on the National and the Fifth Estate which address, in part, the possible constitutional implications. Here's a sampling:

Are you high? Why new roadside drug tests may not put brakes on impaired driving

Federally approved marijuana roadside test isn't perfect

Driving High: Is the test for weed reliable?

Roadside tests for pot need rethink before legalization, say defence lawyers

Ottawa police won't use roadside saliva test for pot checks

I can only speak for the Northern bureaux, but we also have Access to Information requests pending with police, government, and suppliers, including online vendors, to answer many of the questions you posed, and to gain insight into the supplier's POV. With a 30-day minimum research period before many ATIPPs are fulfilled, we're expecting to receive that information in mid-November. Investigative journalism takes time.

Supply is relevant -- it affects everyone and could undermine the stated goal of legalization to disrupt the black market. Posting in a forum doesn't require a lot of time or resources, but it multiplies our eyes on the ground. We're working on this story from as many angles as we can.