We have bought and put together a walk-in freezer/cold store, each have their own through-roof mono refrigeration unit.
Unfortunately when it was removed the wires were just cut, i've figured out most of it.

The defrost drainline appears (from pictures, it wasn't included) to be copper wound in a heating wire. It travels along the back wall from the chiller, through the freezer then forward to the front exrterior wall where it dropped to a sump/pump type thing. I will dispense with the later as i can just run to ground/drains (outdoor shed).

There doesn't appear to have been any fall on the pipe, if i put a fall in the new pipe, and insulate it can i get away without heating?

Both fridge units, have a drain point in the bottom tray, with a cable hanging out of the outlet, one is severed but one seems to end in a sensor, am i right? how can i replace it?

In addition i have the severed temp sensors that hang down through the roof, oddly they appear to splice to a shared multicore cable (using differing pairs of wire). I have no idea why this is (why would they need to travel any distance together?) or where to terminate the sensors on each unit.

I can provide pictures if anyone is feeling generous enough to help me

Many thanks