You can make models in sketch up but they get screwed up once there imported into zmod. Your better off learning zmod or another program like 3ds max. Look in the tutorials section for help on scripting and things like that.
I dont think this idea would even take off the ground. Seriously its like London has no idea what it involves to make a game, little lone what he wants in it....
But the point is its not a mod. To make something like this would take some time to develop and would take people that dont just volunteer there skills without something in return. B2 Bomber and I are currently developing a game and it is hard in all aspects of making the game from coding to modeling and texturing.
The problem with making a iphone app for emergency 4 is the copyrighting issues. You could get sued for every penny if you develop and release it. Plus it would take alot of time and a experienced team of people to create.