[Maédhros]

1. Leave the host to that maniac who just killed his kin. Think what more Fëanor could do in Middle-earth, with himself as king.

Remember that, although Fëanor had claimed the kingship of the Ñoldor, the majority of them still held Fingolfin as their king and if you read the Shibboleth of Fëanor

Fingolfin had prefixed the name Finwë to Ñolofinwë before the Exiles reached Middle-earth. This was in pursuance of his claim to be the chieftain of all the Ñoldor after the death of Finwë, and so enraged Fëanor that it was no doubt one of the reasons for his treachery in abandoning Fingolfin and stealing away with all the ships.

If both of the hosts of the Ñoldor had reached ME at the same time, the majority of them would have taken Fingolfin as their king.

Stay with that maniac in hopes of using your cool, calm, collected mindset to push possibly debilitating actions slightly.

That was actually the mindset of Fingon urging his father to follow the host. The thing is that Fingolfin had to follow Fëanor, for he had given his word to him before.

Then, the Doom of Mandos. Great. Now, his only reason to go on is zapped. No matter what he and his brother can do, tell, or sing to Fëanor, all will go wrong. Why waste all your people in a hopeless quest?

This doesn't adds up. Finarfin knew before that that it was a hopeless quest.
From the Published Silmarillion

But even as the trumpet sang and Fëanor issued from the gates of Tirion a messenger came at last from Manwë, saying: 'Against the folly of Fëanor shall be set my counsel only. Go not forth! For the hour is evil, and your road leads to sorrow that ye do not foresee. No aid will the Valar lend you in this quest; but neither will they hinder you; for this ye shall know: as ye came hither freely, freely shall ye depart. But thou Fëanor Finwë's son, by thine oath art exiled. The lies of Melkor thou shalt unlearn in bitterness. Vala he is, thou saist Then thou hast sworn in vain, for none of the Valar canst thou overcome now or ever within the halls of Eä, not though Eru whom thou namest had made thee thrice greater than thou art.'

At that time, before the Doom of Mandos, the Ñoldor knew that no matter what they did, they could not overcome Morgoth. I want to make a clarification. I did not say that going back was a wimpy decision on the part of Finarfin, I said that it was wimpy of him to go back after the Doom of Mandos was uttered. Lets see the facts:

1. Finarfin knew that the quest of the Ñoldor to beat Morgoth was hopeless.
2. He knew that before the kinslaying, to follow Fëanor was not a good thing.
3. He knew that the Kinslaying at Alqualondë was a horrible act.
4. Finarfin had passed from Alqualondë to the Wastes of Araman following Fëanor.

Now the questions that I make is simple. If Finarfin had this knowledge in advance, why couldn't he make the right decision by himself that he should have turned back inmediately after the Kinslaying of Alqualondë?
To me, he had not the inner strenght to go back by himself, he needed the waring of the Valar to do that.
What if the Doom of the Valar had been uttered after the Ñoldor had reached ME? Too late Finarfin.