Coolant flush questions, N62

[haigha]

It's time to flush the coolant. Last time it was done professionally and I no longer have my good friend and mechanic to help me, RIP.

I've watched several YT videos and read through this water pump replacement guide by @Hayaku: (concentrating on step 41 and forward)

https://www.xoutpost.com/e5344waterpump.htm

I intend to flush the radiator several times with distilled water before doing a final fill with undiluted coolant. Time is not an issue. I got a new cap, brass bleed screw for the expansion tank and blue screw for the bottom. And the undiluted BMW blue coolant.

My questions are:

1. What is the total amount of coolant in an N62 4.4i? Google says 2.2 US gallons.

2. How much coolant drains from the radiator when you open it, the expansion tank and tank's bleeding screw? (need to calculate how much pure coolant to put in at the last step)

3. It sounds like I should wait until the coolant temperature drops to 50-60C before starting a new drain and fill cycle, correct? (I have a Foxwell or could use the hidden menu to monitor)

4. I saw a post where somebody said it's good to run the A/C as well as the heat after each fill. Is that a good idea? I don't see that in Hayaku's instructions.

I figure I will do three or four distilled water flush cycles.

Thanks!