The Silmarillion: Ch 7: Of the Silmarils and the Unrest of the Noldor

[Maedhros]

Bravo Cassiopea. I tip my hat to you.

feel that Fëanor was too hasty in confronting his half-brother, although no doubt the lies of Melkor fired the flame in his belly.

This might bring a little clarity to the discussion:
From Morgoth's Ring: Later Quentas: Of The Silmarils and the Unrest of the Noldor

§52e But even as he spoke, suddenly Fëanor appeared, and he strode into the chamber tall and threatening. A fire of anger was in his eyes, and he was fully armed: his high helm upon his head, and at his side a mighty sword. 'So it is, even as I guessed,' he said: 'my half-brother would be before me with my father, in this as in all other matters. He would not wait for the council, where all words would be heard by all, and answered. He would speak against me in secret. This I will not brook!' he cried, turning upon Fingolfin. 'Get thee gone, and take thy due place!' Then as a flash of flame he drew his sword. 'Get thee gone and dare my wrath no longer!'

Why would the noble Fingolfin not give Fëanor the time for him to defend himself and wait for the council to be ready. What Fëanor did was wrong but, why wouldn't Fingolfin wait for both causes to be stated before everyone.

Did Fëanor foreshadow the destruction of the Two Trees by Melkor and Ungoliant? If Fëanor possessed such precognitive powers, why did he not foreshadow the destruction the Silmarils would ultimately cause?

You could make the same cause with both Námo and Manwë. Did Námo knew that Finwë would be slained in Formenos by Morgoth, and if so, why didn't he do anything to stop it.

Is there any significance in the fact that three Silmarilli were made? Has it something to do with the three themes of Ilúvatar, or something else?

Could be, of course there could be said that a greater parallel exists between the Elven rings made by Celebrimbor and the Silmarils of Fëanor. Maybe Tolkien liked the number 3.

All right, I admit, I don't quite understand this passage. When the Sun passes and the Moon falls, the Earth will be unmade as well (I assume, but perhaps I’m wrong). The elves are bound to the Earth, so I thought when the Earth is destroyed, the elves would die. After all, the destruction the Silmarils caused, surely it would be a good idea to never real their substance, lest another tragedy occurs.

The Silmarils are not the cause of the Tragedy of the Ñoldor, it's the marring of Arda by Morgoth. If the Second Prophecy of Mandos of the Quenta Ñoldorinwa is true, then in the end, when Morgoth will return and the last battle will be fought, he would be defeated once and for all and the New Arda, Arda remade, that is Arda with the marred elements of Melkors cured, will be greater than Arda unmarred, Arda without the Melkorian elements. And it will be because of the Silmarils of Fëanor that the trees will be made again, and all would be good.