Morgoth vs. Fingolfin

[Aiwendil]

Also he was like incredibly angry about his people dyin and Morgoth was just like "Ha i'll go kill this fool" and he didn't seem to care as much execpt that he didn't want to leave his cozy throne room.

Well, not exactly. It says that he didn't want to go, but he had to save face in front of his servants. Because 'he alone of the Valar knew fear' or something like that.

It is stated that he was the greatest elven warrior of all time

Where do you find this? Is it in the published Silmarillion?

As for Morgoth's foot: I always got the impression that it was merely wounded, not cut off. But I guess the passage is open to interpretation.