I am in hot water over cold water in the mornings - secondary kids have a greater affinity for a morning shower then primary kids. The simple solution would be to extend the heating period, but I've sold the idea of adaptive heating based on tank temperature and occupancy.

For that I think I need to add an analogue input device (I only have digital) and sensor.

On the sensor front, what is the recommend device?
How would that connect to Idranet? direct connection or some circuitry ? Is there a circuit diagram someone could share?
Would I get better control with more than one sensor? Where should they be placed (top and bottom of tank, flow return from tank ?)
What is the best method to fix the sensor to the pipework? Assume once fitted it should be covered in insulation? Or does that impact responsiveness? Is that important?
I assume I leave the existing thermostat alone as protection, so maybe turn it up so it doesn't affect normal operation.

Wisdom from those who've done this much appreciated