One note about Kumori: This might be a veeeeeery long shot but technichally, you don't have to work with free willed beings to use necromancy. If she has been careful like a... well madwoman, she could have developed her abilities by draining the ambient life and using it as fuel instead of dense fuel rods (ie humans).

Maybe she can do things that take enough power equvalent to a blood sacrifice (1, Male, Adult, Any Ethnicity please) by turning 13 acres of grass yellow.
All we can be absolutely sure about is the little fact that necromancy (like mind magic) is extremely easy to abuse and follow to a dark path.

Edit: And no, in the book the guy on the ground had just died. Brain death occurs somewhere between 60 and 300 seconds after heart stops pumping blood. You could argue that all she did was empowering his whole body (minus the brain) externally so it could overcome the shock effects of the wound. It is this close (__| |__) to the border but I would argue that act wasn't actually a lawbreaker. (Just a massive use of cold magic. Edit 2: sorry I call necromancy cold magic.)

Laptop (or if you are lucky to have the book, the book) with important pages bookmarked; Skills, Stunts, Powers (If you are allowing them to choose their powers) and get them look at them to make the character fit.  
Little character story write-ups (If you are using pre-gen)
Magic Marker and a big plastic covered sheet for the middle of the table to draw upon (maybe 1 or 2 maps of the area prepared in the same way)


For the story, I think the Lazy GM works best in cons. Prepare a flashy entrance (to be played about 5 min into the game) and a satisfying end sequence (mine had being debriefed / thanked by wardens while mecdicos checked people scene, a classic "after the bad guy dies scene" done in White Council style ) Drop a couple of hints (The city sheet is wonderful for this) and let the players run wild with it.

To get the group together, you can use the "old pals" aspect (2 players are old pals, one knows the 3rd player and so on) or you can just use the flashy fight scene to throw them together and don't let them get off. (Unless someone is out to be a dick, you can get them together via broken down cars, traffic jams, police barricades and internet chatrooms .

I thimk most people misunderstand the "jack of all trades" aspect of pure mortals. A JoaT character will never be able to hold his ground against specilised chars (Like Bard the seventh character in 6 man group in DnD).

The Humans in DV are jack of all trades because they can specialise in anything, not because they can do it all at the same time. Your average supernatural will try to clean a vamp den with fire and shotguns. Your average mortal will call in support that can range from a SWAT team to a platoon to an airstrike. (Side Note: Why do you think Militaries around the world are so insistent on heavy caliber tank guns and precision bombs? The fact that they can kill other tanks is a side benefit.) to act as bug exterminators armed with holy water and shotguns. (Shotguns rule! Disclaimer: Only in close quarters and up to 10 meters)

Yes, it's the different tastes issue. There isn't any "right" aswer. Still "I" would rule that those guys can and a mortal can't becouse he is a "mortal" he is supposed to be the baseline after all.

maybe add a downside like "distracted" as a non sticky aspect to the user (or worse) as Harry sometimes gets with his sight.

Now that I think about it, you could pattern it on the "Sight" power, dealing with hearing (to surface / radiating thoughts) instead of seeing...

Of course there isn't negative tresholds (maybe a desecrated and linked to underworld place, an unholy shrine in other words, might have such a thing.)

Userisk, what I meant with +0 / -0 business was what harry was talking about in WN. The hotel was an open public place so there wasn't "any" usable threshold to build a ward upon, ie an effective score of N/A (Not usable).
Compare this to a new bachelor home / frat boy sorority house , Sure the place is barely better than a hotel and it has an effective value of 0 but there "is" a treshold that you can build your spell wards upon it.

I would argue that Edinburg has at least such a usable treshold to build upon.

I know, I know but I do know a bit about guns in general and such stupid, showy hollywood stuff makes my "correction nazi" wake up

Belial, that is so wrong on so many levels...
First, except a couple of stances like Macedonian, dual wielding is completely useless. Even such stances only allow you to put down supression fire using handguns in short ranges (up to 5-6 meters at most), slightly better than spray and pray but not really effective if you are trying to take down some ones.

The Way of the Handcannon... There is a reason why 9mm and 45 acp are the most used pistol calibers in the world. They deliver a nice balance between stopping power, recoil and clip size.  Sure if you have inhuman strenght you can use beigger caliber weapons as normal pistols but for normal humans, you need to slow down and spend more time on correcting recoil when you use a handcannon.