[Formendacil]

As regards the Valar coming to the aid of the Edain...

I wouldn't be so certain that they wouldn't have gone to war. They went to war against Melkor when the coming of the Elves was imminent, for their sake, despite being rather slothful and inward-looking in Valinor before that.

Personally, I think that had the Noldor not marched off to Middle-Earth, the Valar would eventually have shaken off the cobwebs of feat (no doubt prompted by Ulmo and Tulkas), and made war for the benefit of Men, who would now have awakened, so that there would no longer be a fear of hurting the unborn Men in their resting place.

Furthermore, the situation as it would have been in Middle-Earth at the time of Man's awakening had the Noldor not come to Middle-Earth would have been extremely similar to the situation there after the fall of the Elf-Kingdoms in Beleriand, and the extermination of the Elves at the hands of each other in the 3rd Kinslaying.

It might not have been Earendil's plea which stirred them, but I think the Valar would have had to come back to war eventually. And with no Ban or Curse on the Noldor, they would not have had their pride to urge them to stay at home, but rather to urge them on.