tracking the particles

I am having trouble with my particles. I want them to be able to go in a straight direction( in a Y direction) but then rotate the circle so that the particles now emit going down ( -z direction). The problem is, is that i had the particles going at a Y direction of 5 and a life of 20 with .2 random and 0 normal. This allows my particles to emit straight in a Y direction but if i try rotating them to a -z it still goes Y. I know why i am experiencing this problem. It is because i have the Y value at 5. Without that Y value, the particles will not emit straight but will emit outwards in all direction.

So does anyone know how to fix this?

I found a way to make the particles emit the way i want them too without using the global directions. I made like a quick 60 second animation of trying to have the particles track to an object and then rotate the object so that the particles change directions. Unfortunately i does not work, the circle will rotate but the particles emit in the same direction. Also, if you notice, some particles are just randomly flying off, why is this happening?

Also, i am having problems making a good particle color for an exhaust. Does anyone recommend a way to make a good thrust particle emitter?