Hello, how are you?

One of the first services I want to do to the HGT is to flush the coolant from the engine, fit a new coolant expansion tank and new coolant.
I have a few questions as it is the first time I will flush the coolant from a car.

My plan is to first get rid off as much of the old coolant as possible.
Then do a cycle of either distilled or ionized water,
Then do another cycle but add some Liqui Molly cleaning additive to the water.
Run it and then flush it.
Finally get rid of the old and dirty expansion tank, fit the new one and add the new coolant.

Does my plan sound right?
What is the best process to do the flushes on the HGT to make sure most liquid comes out, including the heater core?

What is the best solution to do the clean flushes? Distilled water?
Also, for the new coolant, I am thinking about going with Paraflu as it is the recommended one by Fiat.
Should I get it diluted and ready to go on 5 liter bottles? Or concentrated on 1 liter bottles?

Any other tips I should follow?
Thanks you.

Unless it's full of oil and debris I'd empty it out fill with a hose run for a few mins then fill again with mixed coolant

I agree with , chris3234 cleaning the radiator and engine with a garden hose should be enough.
I am not sure if the cleaner will accomplish must if the system is already clean.