Elements are flavor.  All they do are satisfy catches. 

Nine words containing two mutually exclusive points. That's some impressive brevity right there. Or maybe you are using a definition of "flavor" that means "uncommonly occurring but still tremendously advantageous mechanical benefit"? Should we alert Webster's?

As written.  It would take me 10 sec to think of any effect you could want with earth or spirit, 15 sec for water or air, 20 for fire.  That's hardly bogging down a session.

I'm very happy for you. Not everyone thinks this fast. My "ten minutes" was intended as hyperbole, but I have yet to meet a gamer who enjoys spending excess time so the guy with special circumstances can resolve his fancy action.

Final point--spells are not solely defined by the effect they create, but also by the situation they affect. If a pyromancer wants to throw up a shield spell in a dry wooden building, you can bet your ass that I'm compelling the "Highly Flammable" aspect on the walls. Many forms of Earth magic manipulating actual dirt or stone is ripe for compels, where simple kinetomancy creating stony force barriers would be less so.

I'm doing New York myself, and I have a lot of material, admittedly produced under the heavy influence of "the Vancouver method". I'll start with my Themes and Threats, and if you want more, I'll be glad to provide.

DIRTY MONEY, DIRTY STREETS (Theme)
The Idea: The city falls prey to crime and poverty while the rich hoard ever-increasing wealth.
Face: “Big” Ed Biggs, Ruthless Crime Boss

WORMS RIDDLE THE BIG APPLE (Threat)
The Idea: New York has a tremendous density of supernatural predators, all seeking sole access to their prey.
Face: Utapishtim, Ghoul Prophet

IF I CAN MAKE IT HERE, I CAN MAKE IT ANYWHERE (Theme)
The Idea: Power abounds in New York, but only the toughest survive to seize it.
Face: Thrymm, Jarl of the Jotnar



THE STATUS QUO
Supernatural: Predators bicker for power and prey while the clued-in mortals do their best to flee or weather the night. Meanwhile, the Goblin Market supplies all sides.
Mundane: Making money and taking money—New York’s principal business is business.

Of all the Catches I would consider, possibly the least likely would be massive trauma. The Einherjar used to make a daily game out of killing and dismembering each other, before going back to that pig made of infinite bacon for lunch. I forget what it was called. I think there was a cow that made mead inside its udders too, but that's hardly relevant.

I would probably give the Einherjar Supernatural or Mythic Recovery, but with the Catch of "In Valhalla." It's a pretty harsh Catch, and would make the power all but useless--in the normal ways one thinks about using it. Consider the discount provided by such a harsh Catch (I'd place it at +5) makes it possible to buy Mythic Recovery for almost nothing. Then remember that the Uberghouls are listed in OW as being functionally immortal--not even massive trauma from Holy Hand Grenades will cut it. What this means is that an Einheriar is not much scarier than a Pure Mortal in combat--he'll have less Fate Points, but will balance this out with a plethora of combat-related Aspects to invoke and high Skills--but he is almost impossible to permanently put down. If his comrades manage to bring back so much as as his severed head or shattered femur to Valhalla, he's coming back. And he's probably very, very angry at you.

I heartily disagree that elements are just flavor. Certainly, you're very unlikely to need all five, and four is often overkill, but between the need to satisfy Catches and the need not to bog down a session for ten minutes trying to justify the action you want to take with your available elements, they are very handy.

That being said, I prefaced my suggestion by stating that it was not intended as a "go to" interpretation on the default rules. I could have been a little more clear, I guess. So, here goes clarity: That suggestion was made purely to illuminate an alternate viewpoint. In no way do I consider it canon or RAW. I just wanted to showcase an interesting idea from a viewpoint I had not seen previously.

Whatever is decided, I would make a point of emphasizing to your players that this is not WoD. Vampires are not tragic figures, cursed by a choice not their own. Every single full Red Court Vampire is a murderer, and killing is viewed as a lot more of a serious issue than WoD tends to hold it as being. The Hunger drives them to their first kill in many cases, but the themes of personal responsibility are among the strongest ones present in the series and 'verse.

Furthermore, the WoD, in my experience, encourages you to play monsters--not monstrous templates, but monsters in a moral sense. It encourages a bleaker view of things like necessity and survival than the Dresdenverse. I don't view this as inherently a bad thing, as role-playing goes--I don't believe for a minute it will influence the real beliefs and behaviors of a stable person to make believe that he's  an inhuman nightmare once a week. But it involves vastly different genre assumptions that the DFRPG.

Speaking of Even Hand, I'd love to see your take on or more

Under Scrifices: So people are worth +20, what would the sacrifice of a live chicken be (I've seen +2 in other posts)? Do you get more for a goat? Is there some way to calculate how much any particular being is worth?

It's based off available consequences. It's perfectly reasonable to assume a chicken cannot take more than a Minor Consequence (2 shifts). Similarly, humans are worth 20 shifts by default. exceptionally hardy specimens, with high Endurance ratings and a consequence-providing stunt or two, will be worth even more.