There's a book out there, Shadows Fall by Simon R. Green, that has a town where the old concepts go to die. Characters from the children's book from the 1920s are there, waiting for their memory to die which will cause them to fade away into nothingness.
I can see Toon Town working the same way. Images from pop culture generating enough emotional energy that they imprint themselves on the Nevernever. Cartoons, especially the cartoons that charge up children, could easily have created a realm in the Nevernever where they are real. Where safes fall from the sky to smash people - who get smashed flat then re-inflated.
It should be possible to create all the cartoons, borrowing heavily from fairy powers - with restrictions. For example: Bugs used to glamour himself into looking like a beeeautiful lady but the glamour only worked on other toons (usually Elmer Fudge or Daffy Duck), so maybe a catch of "Only affects other Toons" would be good for their powers . Alternatively they could be like how the Fae are limited and unable to affect anyone who hasn't signed on to cartoon logic.
I would definitely give every toon a form of 'unkillable' but also give them a ban on really killing normal people (including PCs, but maybe excluding monsters). They can lay a beat down, but if you accept the consequence of "seeing birdies" then you're back up for the next scene.
Richard