So one convoy lost = war lost?

Yes, the first
several convoys are going to take more of a pounding, while you get your Aegis subs into position, but then, you can attrition their bombers very heavily (and their tankers) and those that don't get shot down have to still have enough fuel to RTB, so expect many more to be lost to running out of fuel over the ocean hundreds of miles offshore. And even then, those few that do survive, will no longer have many tankers left (as the tankers are slow, they will probably suffer heavier losses than the bombers), and this means that even fewer bombers would be able to strike at the convoys for lack of tankers.
Also, consider that there are many convoys to provide cover for, as well as several CBG, but only one ambush site needing to be covered. If one tries to divide a greater number of hulls between a dozen or more potential targets, as opposed to massing them along the return path, then you get a lesser return rate, plus, you are not actually killing their bombers at all, so you still take greater losses amoung the merchant ships, as the missile threat is not being reduced.
No, they really wouldn't. I must not be explaining this very well or clearly, for you to precieve that that would even be a possibility. I am not proposing that the Aegis subs would form an outer 'picket line' just north of the convoy lanes, nor even 100 miles north, but rather, well north of Iceland, where the Soviets think they are relatively safe, their bombers fuel reserves are about at their lowest,
and their tankers are nearby. And as the mission has already launched their missiles (or decoy drones), they have nothing left to sucker the Aegis subs, who they don't even know are there. So no, the subs will not be suckered by such a ploy.
And still could be, on top of getting creamed before they even got to their bases.
Well, if you want to accept the risk of sitting right off the soviet coast, and possibly panicking them into launching ICBMs at the US, in the mistaken belief that the initial missile boost phase was SLBM and not non-nuclear cruise missiles. Not to mention the greater and greater risk to the subs themselves, and the fact that many of the bombers could be repaired, because they were damaged on the ground at their airfields, rather than 100s of miles offshore.