I'm looking of a Dresden files game in the Detroit or Sterling Heights/Utica area, preferably one with a local setting.  I'm willing to GM or be a player.  I've got my own books and plenty of experience playing and DMing in other systems.

Not really.  Designing a character to use the same element for attack and defense is vastly more effective than using two elements, since your specializations can apply both ways.  And if you can't apply specializations, then you can't have other types of magic.

Conversely, fire magic doesn't really have too many offensive advantages over other elements, so there's no special reason why it should be disadvantaged defensively. 

Not within the game rules maybe, but within the fictional world it does.  That's what I mean, the things we're talking about, messing with probability, transferring kinetic energy into heat on the fly, maintaining fire hot enough to not only melt metal but dematerialize it, ect., are all incredibly taxing uses of magic where as compared to summoning a wall of spirit/force, or using physical material to intercept or deflect attacks (earth, water, air).  Conversely fire is always dangerous to human flesh, whereas the other elements are only dangerous in certain situations.

But here's an idea, rather than converting the kinetic energy in the projectile to heat in the air, why not just convert it to heat in the projectile?  That way your only changing the type of energy, not it's location, so the magic is less complicated.  Of course if the monster throws a propane tank at you, that could be bad.

I like all the idea's here, but the really effective defenses, the ones that aren't just veils (which is not to say that veils aren't effective defense, just that they're in another category), seem like they would be super costly in terms of power and control.  Fire is probably the lest defensive of all the elements, it's a destructive force primarily, and a cleansing force secondarily.  Harry himself, who seems to use fire as his primary element, uses spirit/force for defense.  Unless you're really restricted to one element I would pick something else for defense. 

Still I really like the idea of converting the kinetic energy of bullets and other projectiles into heat, though there are some issues with that.  Assuming your still human, your in danger from the heat your shield generates. If you have to stop incoming fire from fully automatic weapons, or, say protect yourself from an explosion, you might find yourself without body hair and your clothes on fire.  And what if you need to stop a fire attack?  Sure you can stop whatever is on fire, petroleum jelly or whatever, but converting the kinetic energy to heat little more than a foot from you may make the attack MORE effective, not less.

Here's another consideration: what if the giant troll needs to go down NOW before he hurts the kid.

With a higher conviction you're going to be able to put more power into your spell, and you can absorb the excess over your discipline with psychical stress and consequences, leaving mental stress and consequences to boost the spell even more.  With a lucky roll and the use of fate points, you can control the spell.

The discipline guy is gonna be close in power to the conviction guy, but he is gonna be a little lower.  He'll be able to keep it up longer, and be more accurate in the long run, but you only have 1 action to stop the monster.  He can use his fate points to boost the power, but then he has a harder time controlling that power, since you can't use the same aspect twice on the same action and you only have a limited supply of FPs.

Another bonus to high power low accuracy hit as opposed to multiple low power hits, is that when you do hit, the defense of the target only reduces the power once.

I'm having a hard time keeping it all in my head.  What would really help is a demonstration.  Anyone know of any play-tests or games that have been put up on youtube?

Fists (or alertness)

WN Chapter 2
With no warning whatsoever, Murphy moved, spinning in a blur of motion that swept her leg out in a scything, ankle-height arch behind her. There was a thump of impact, and the sound of something heavy hitting the floor. Murphy—her eyes closed—sprang onto something unseen, and her hands moved in a couple of small, quick circles, fingers grasping. Then Murphy grunted, set her arms, and twisted her shoulders a little.  There was a young woman’s high-pitched gasp of pain, and abruptly, underneath Murphy, there was a girl. Murphy had her pinned on her stomach on the floor, one arm twisted behind her, wrist bent at a painful angle.

(If the whole thing is too long consider just using the part in bold)

Driving
PG Chapter 4
I wrenched at the steering wheel and the brakes, my body responding to things my stunned brain hadn't caught up to yet. I think I kept it from becoming a total disaster, because instead of spinning off into oncoming traffic or hitting the wall at a sharp angle, I managed to slam the Beetle's passenger-side broadside into the building beside the street. Brick grated on steel, until I came to a halt fifty feet later.