That sounds useful, but what does it have to do with transforming people?

Isn't a transformation spell an attack, with the transformation occurring when all consequences are filled?

Interesting idea.

So what does Sponsored Magic: Lawbreaking do, mechanically?

It's pretty flexible- doesn't really follow laws.    It can let you cast spells in any evocations or thaumaturgy domain that that you don't  normally have (example, a Wizard with Fire, Air, and Spirit would be able to cast Earth and Water spells thanks to the Lawbreaking Sponsorship).

We use a rule where you can get access to an additional bonus fate point for every point of Refresh, and it translates into a point of debt.  As a general guideline, you won't get more extra points than your Refresh value, because at that point, the Sponsor may as well just it themselves.  (Example, a 16 point character with a sponsor can get up to 16 extra points of Refresh).  Each point of debt is effectively a banked compel that the sponsor can use against you to achieve it's objectives.  The more debt you have, the more hold the sponsor has over you.  You burn off debt by doing what the sponsor says.  With Lawbreaker, you burn off that debt by using magic to break laws.

FYi, Dresden Files Accelerated RPG  uses New Orleans as an example setting.

The Paranet Papers supplement has a write up on a Were-Gator, as well as an entire Florida swamp community setting that you could easily import into the Louisiana Bayou.

Can a Fetch change its Catch with True Shapechanging and Modular abilities?  For example, if it shapechanges into a vampire, can it transform its Catch vs [cold iron and summer magic] into [sunlight, holy attacks, fire and stakes to the heart] and lose the previous vulnerabilities while in the vampire form?

Temporary powers cost 1 FP per refresh spent.  Some GMs will let you replace FPs with free tags from appropriate aspects. 

So, if you are using ritual magic to gain inhuman toughness, you can cast a ritual (I think most people agree the complexity should be enough to take you out physically (around 5 shifts) then you need to spend a FP for each point of refresh (2 for inhuman).  That boosts the complexity of the ritual to 9 and the power will only last 1 scene. 

Or you create an appropriate aspect for each refresh (resilient bone structure' and 'increased muscle mass', for example) its 3 shifts of power for each maneuver, so it's a  more expensive ritual than paying a FP. 

Having the power work beyond a scene requires extra shifts into duration and would probably require you to spend a FP or tag an aspect to activate the power every scene after the first until the spell duration runs out. 

If you have sponsored magic or some kind of sponsor power, you can just grab powers from your sponsor but you accrue debt instead of spending FPs for each point of refresh and they only last one scene.    But, in general, having a sponsor can be a justification for buying temporary powers with FPs if it's fitting for the scene and the GM agrees.

I like this mechanic.  Is it a house rule, or is it from one of the rulebooks?

This might be  fun build for you to use, assuming 6 Refresh and 20 skill points.

High Concept: Hardboiled Psychic Detective
Trouble: Dead People are complicated

Background: Transplanted Psychic Abilities
Rising Conflict: Advice from his heart donor's shade
Other Aspects: The last thing they saw, Let's check out their old haunts, Dead Broke

It would also be fun to have him investigate murders through interactions with the ghosts of the murder victims.  And as for the Sight, again it would be limited to the donor shade giving him input about the surroundings.  Rolling would help him not be overwhelmed, as usual.

Powers:
[-1] Ghost Speaker,
[-1] Psychometry
[-1] The Sight
[ 0] Cassandra's Tears

Stunts:
[-1] Psychic Clues: swap Alertness for Lore when using Mystic Perception
[-1] Hard-Boiled: +2 Discipline to Control Emotions

Skills:
Great(+4): Alertness (Mystic Perception)
Good (+3): Discipline (Control Emotions 5), Investigation
Fair (+2): Athletics, Contacts, Guns
Average (+1): Conviction, Endurance, Lore, Scholarship

Stress:
Physical: OOO, Mental: OOO, Social: OO

Spent Refresh: -5

The write up for Jo Theed could be optimized a bit by making him more of a shapeshifter.

Jo Theed, revised:

High Concept: Dragon Disciple Jeweler
Trouble: Dragon is a taskmaster
Template: Emissary

Stunts: None

Supernatural Powers:
Marked by Power[-1]
Beast Change (Wyvern) [-1]
Human Form, affecting [+1]
Claws [-1]
Wings [-1]
Inhuman Strength [-2]
Supernatural Toughness [-4]
The Catch: Weapons that can pierce dragonscale [+3]

Total Refresh: -6

Skills, Human form:
Great(+4): Craftsmanship
Good(+3): Presence (+4 with Marked by Power), Resources
Fair(+2): Lore, Rapport (+3 with Marked by Power), Intimidation (+3 with Marked by Power)
Average (+1): Athletics, Discipline, Endurance, Scholarship

Skills, Wyvern form: 
Great(+4): Fists (+4 dmg w/ claws and Inhuman strength)
Good(+3): Athletics, Intimidation (+4 with Marked by Power)
Fair(+2): Alertness, Endurance, Might (Lift 5, Grapple 3)
Average (+1): Discipline, Presence(+2 with Marked by Power), Stealth, Survival
Stress
Human form: Physical OOO, Mental OO, Social OOOO
Wyvern form: Physical OOO[OOOO] 2 armor, Mental OO, Social OOO

Jo is a skilled jeweler who came to the attention of a True Dragon for his artistic ability. The dragon made Jo an “Emissary,” though mostly he has just been granted the ability to shapeshift into a small Wyvern to defend himself and his jewelry from the dragon’s enemies.

The main narrative point of the Web fluid was always as a limitation, something he runs out of randomly and has to go and re-brew.  Would it be possible (or advisable) to instead do webs as Brewed Potions? 

He has hundreds of charges of Web Fluid so he'd need something like Refinement in the hundreds to reflect the quantities of potions.  It's more accurate to treat those scenes where he runs out of web fluid as him getting a Fate Point for an Aspect used against him.