Do alot of people go there to watch the fireworks for New year's?

Yes

It can be really icy in the winter if it has snowed. I just hiked it and slid down in many places. Wear boots with lots of traction.

Yes people do go.

We did the trail in June, well before the 4th of July but it would be a beautiful vantage pt. to see fireworks. Only draw back would be the 3-4 hr trek back down in the dark unless you camp overnight. It would be a tough trek in the dark.