On Halloween there is a huge parade in Greenwich Village located near NYU. Now this is not just a parade, it's an outdoor event with several closed streets involved. Let's say it's really a Cosplay event.
Check out their website: https://www.halloween-nyc.com/
As for places to eat and you would like to venture to Brooklyn. It's really not that hard. There is a place that is totally Geek.
It's called Action Burger. They have everything you want and more.
Check out their website: http://actionburger.com/
For you Anime buffs. There is a website for anyone that is going to NYC should check out first before taking the trek in.
Website: http://nyc-anime.com/#events