Regarding flex/derate/assumed take off:
You cite best industry practice. Well, it's not completely true. With the EK software, you can only go for full thrust or max reduction. Any in-between, which is used a lot elsewhere for a little more safety margin but not full thrust, is not recommedable here, because the gross error trapping procedure a la EK will no longer be possible. It's not in the SOP, so either full or full reduction, which I believe is not best practice.
EK SOP = max or no derate?
Why?