Wow, this is a lengthy, dizzying question. Where to begin?
>Is living in this city really as bad as it looks on paper?
I think the answer is no. Not as bad as it looks on paper. 3 things I would keep in mind:
1) The crime rate is way down in NYC (as it is in other big cities), to the extent that it is one of America's safest big cities. This is not to be underrated.
2) The subway system is creaky at times but it runs 24/7 and rarely has significant delays (I haven't had more than a 10 minute delay in months and months and months) and despite recent price hikes, it's still an absolute steal. It will get you just about anywhere you need to go in Manhattan, and it's awfully helpful in Brooklyn, Queens, and the Bronx as well. It keeps the cost of living down, bigtime.
3) Rent IS exorbitantly expensive in New York City, disporportionately exorbitantly expensive in Manhattan, only slightly less so in some of Brooklyn, but semi-affordable in other Brooklyn and Queens nabes. Rent costs (or the cost of buying an apartment or a house) is a great reason to NOT live here.
That said there are neighborhoods like Astoria in Queens that will never be all that excessively pricey (for a variety of reasons beginning with the architecture, it's unlikely that Astoria ever becomes a truly gentrified expensive hipster/yuppie nabe), and I've seen plenty of people (myself included) move to NYC and find an apt to rent in Astoria (which has plenty of charms, and is an easy subway ride into Manhattan) and stay there for at least a couple years until they get their bearings/savings.
>could one survive on $24k (with obvious auxilary job(s))?
I survived on less my first year in NYC. But that was more than a decade ago. I think $30k or so and you could squeeze by, depending on your standards.
>average length of time the buzz lasts before reality has a hand on your skinny behind;
Buzz has lasted and lasted. Is it nice getting out of town for a weekend now and then? Sure, just like anywhere else. But New York has mostly become a *better* place to live in the last 13 years since I've been here. Capitalism has its share of flaws but the dazzling, fierce competition here is beneficial to the consumer of food, booze, music, etc. Many people, myself included, struggle to imagine living anywhere else once they have lived here. It's that great. Though I acknowledge those last two sentences can sound annoyingly proud/elitist.
1) It IS important to find a liveable apartment in a not shitty neighborhood right when you move here. The people I know who seem to have the worst experiences living here are the ones with the worst apartments in the most isolated neighborhoods. These are cheap apts, of course, but their quality of life is so negatively impacted by these places that they don't seem to fall in love with NYC like they should. Safe and relatively clean Astoria rules over some shithole studio above a fishmarket in Chinatown, probably, even if the Chinatown fishmarket is closer to some cool new bar.
2) For the most part, it's fantasy to think you can find a job here without moving here first. This happens rarely, unless you are either really well-connected or some sort of hot commodity. If you're serious about living here, you save money, move here, get an Apt, and begin interviewing for jobs. You'll be far more likely to find jobs if you already have an NYC address. Perhaps this is blindingly obvious stuff, but I'm amazed by the number of people I've met who say they want to move to NYC but are hoping to get jobs here by just randomly applying for them while still living a time zone or two away.