[solemnlyswear]

> The moment I withdraw my consent all telemetry and data collection should stop.

You can do that by simply going into about:preferences#privacy and unchecking "Allow Firefox to send technical and interaction data to Mozilla"

> I shall be able to see all the telemetry data in its full glory to make my own assessment of what's collected and how.

That's all available in about:telemetry

Firefox is open source and so is the set of telemetry it collects, the schemas are published openly on the web. Every request to add new telemetry is reviewed in a public bugzilla ticket. It's not a mass of dark surveillance capturing unknown information, it's all done in the open in public.