I just have to say I have really enjoyed this discusssion. I am really too new to offer any help to anyone, {I'm the noob that always asks a ton of questions}, but I couldn't pass on telling everyone how much your discussion (especially in the question and answer format, imagine me saying that !) has helped me understand the huge, almost insurmountable obstacle a noob like me will be facing on Immortal level. It'll be fun to try.
I am sure many lurk here and learn, too, without posting. So, it is very helpful to many of us. By the way, for me at least as a noob, the questions that are asked that may seem elemental or noobie, are just as important, because many of the answers are the same things this noob was wondering about before the question was asked.
As a 'real' noob, I guess the one question that the whole discussion begs for me is whether it is just almost imperative to either cripple or take out any enemy so early ( I haven't been particularly successful with early rushes of any kind yet in my games). I.e., straight up infrastructure and settler and building barracks etc. with regular development and planning for and preparing over time for war later is ... as I am understanding from the above .... just not a reasonable course of action on Immortal level (because of the AI's great starting bonuses, and fast development rate?) I presume one would just fall too far behind in each area (military, techs, cities, territory, population, etc.).
Thanks again to everyone for the input-- at least when Immortal kicks my butt I can't say you didn't warn me properly!!
Luck to all,
Adama
Military Leader of the last remnant of the Human Race