the Pool first vs hatch first optimization

Hmmm I definitely agree with your decision for the most part in platinum and higher league play. However, overall the decision between pool/hatch first actually doesn't change a lot. With the pool first you get your first queen a little faster and a pair of lings or 2 sooner

With hatch first you sync your queens near perfectly and can get your 3rd overlord a few supply later allotting you a drone advantage.
That being said a pool first is a safer option due to getting that first queen up sooner for defense and the option to spend 1-2 larva on some lings if necessary. The other important note in my opinion is with hatch first, the drone/larva advantage is pretty much negligible because with pool first you get an earlier larva inject. 
That being said the pool doesn't go down THAT much later but the risk factor of taking damage from super early rushes goes WAYYY up; with hatch first you need to have perfect drone micro/control in order for any advantage from your choice to get pool second to still stand. If you don't have solid drone micro and great macro I would completely advise against going hatch first for these reasons; not worth the risk for a very slight advantageous position. With all this in mind I still agree with your overall decisions in higher league play that is.
Much love,
-CovertMuffin