In incline to read Mother Summer at the Gates as saying that Winter holds this duty in this age of the world, as it were, but that there have been other before; that and Rashid appearing to talk to Harry in a manner consistent with being linearly timebound to their previous conversations appear to me rule out the no-space-and-time posit on the Outside.
I don't believe that the area outside the Gates is truly Outside, nor truly part of the Never Never. Rather (in my opinion) it's an in-between place like Chicago-ove-Chicago or the Valley of the Stone Table. I agree with you that time and distance appear to be nice and stable there, which is probably something the Gates are designed to accomplish so that the defenders are actually capable of defending instead of succumbing to madness trying to navigate the
Non-Eucledian Landscape (TVTropes Warning).
If there is only Here and Now, if there is action (as we see in the attack on the Outer Gates), it implies purpose, and for there to be Purpose, there must also be consensus.
Not following your logic here either; does a spinal reflex pulling away from a flame imply purpose ?
Apologies for using anthropomorphic speech. They should have sent a poet, but alas, I'm but an engineer. What I mean by purpose does not necessarily imply that there is sentience or reason behind it. Your quote above is a clear example of purpose without reason (namely, evolution). Another classic example is a bubble's circular shape (with the purpose being that nature tends toward the lowest energy state possible, no sentience required). I suppose I could have used "reason" instead of "purpose", but that word is even more correlated in my mind with sentience, so I stuck with purpose.
In any case: try to picture a situation where secrets are impossible. Where your very name reveals every aspect of your being. Where it is impossible to go into the corner and work out an alliance with a few; where everyone hears everything you have to say in favor of some action, and has already heard it all before, so you are incapable of changing his mind, and you know you are incapable of changing his mind, because he has no secrets from you, either. There are but two possibilities I can envision: total chaos, as that only available instant of indecision becomes permanent, due to lack of advancing time. Or unity of purpose, as some sort of consensus is reached that has always been reached and will have always been reached (again, when I use the word "purpose" here, I don't imply all the beings on the Outside are sentient, held a vote, and reached a decision, so much as they all obey the same rules of nature, as it were).
I propose that the beings of chaos of the Outside, when they enter into the non-chaos of our reality, becomes somewhat like Harry's description of goblins in Changes: all different, yet curiously similar. And that's why they all seem to act toward a single purpose: it's not so much a choice they made, as an inevitable rule of their nature.
On largest-scale goal, perhaps, but on strategy, and smaller goals along the way?
That is certainly an interesting question: are all those infected by Nemesis connected? Did He Who Walks Before recognize Harry as He Who Walks Behind did back in Blood Rites?