The fire is made using voxels rather than a partical system, if you check out version 1 in alternate versions you can see where it appears to pixelate, that's the voxels, the lighting is fucked up because I put the light parallel to the tori witch I'll avoid in future, if you check out version 2 in alt version the lights are at an angel and look better, the
glass tori is made using caustics, so yes it is supposed to look like glass :P those who pay attention to detail will also notice the glass isn't solid, but shells.
C4D is a bit meh for me i prefer 3DS MAX or Maya, i'm an auto desk fan boy :P
as for smoke i could easily add it but in this scene i didn't want smoke, heres an example of fire with smoke: