1) (Newbie Questions) How would you go abouts turning an emitter (especially fire which appears to have a fixed emitting speed) on or off at various keyframes.

2) (Newbie Question) How would you go about creating and destroying (or showing and hiding) an object in a maya scene throughout various keyframes. (without keyframing the object to appear from behind the camera)

3) (IMO: Not newbie Question) How would you go about keyframing shader-changes in a Maya scene?

Say you have a beaker model in Maya, and you drop an object in it. A particle emitter turns on at that point to create a cloud raising upwards, the object disappears, and the fluid in the beaker changes from a blue to a red color. (Example which covers all 3 questions -- not the animation I'm using it for though :b)