3 Questions on Particle generation

I am trying to figure out three things with the particle systems

  1. Are there any strategies for animating/generating particles on Twos?

  2. Is it possible to make the particle generation independent from the camera. If I have a particle system and I zoom in close with the camera peg, it maintains the size of the particles relative to the plane. I have attempted connecting the camera peg to the plane peg-input and that successfully shifts the size of the plane, but still changes the size of the particles so that they are always the same no matter how zoomed in

  3. I have been looking through the docs but am unable to find if what I am looking for exists. Is there a simple Node that allows you to set a number and connect that number to multiple Nodes as a value? For instance, if I have 6 different particle Node groups and I want to set the value of “Number of Particles” on all of the Sprite Emitters, is it possible that I could set that value in a single Node and control all of the Sprite Emitter values for the “Number of Particles” property on all of them?

Any help or ideas would be appreciated