How far can you stretch 100k in ny?

Getting a roommate is going to be your best bet. Outside of that it just goes down to the same advice in every cite. That would be using hand me down furniture at first. Limiting how much you eat out, pregaming before you go out drinking, etc.. also, just general advice make sure you’re watching subscription services, you’d be surprised how many people blow 1000s of dollars a year on stuff they don’t use.

for NYC specifically, financial district, kips bay, and Murry Hill will probably be your best bets for cheaper rent, and you’ll probably want to avoid areas like tribeca and hudson yards

Try to keep rent around $2k and you’ll be fine

Its quite windy in NYC , most of your dollars would be blown away by the wind before you could lay them all down.

Not far enough. Agree with get roommates. Lever up short-term and enjoy life. You will be fine in longer-term. 

It's very reasonable to save around ~1 - 1.5k a month without living particularly frugally on the IB analyst base largely due to the lack of time and the dinners being comped. You can maybe get this up to ~1.8 - 2k if you are a bit more frugal, but not sure if that delta is too relevant in the longer-run. Most first-year IB analysts are paying somewhere from ~2300-3000 on rent with roomates at least among my pretty big sample size of friends who just got into IB.