Low Poly Jet Engine particle effect

I had an idea for a particle effect that I would make that was meant to look like a jet engine or something of the sort, I got the idea from the new rocket league trails, here’s the one I saw: https://www.youtube.com/watch?v=e0v2GXqwD0s
I was also looking at this blender stack exchange post for a way to change the colour of particles with age: http://blender.stackexchange.com/questions/8052/how-do-i-get-particles-to-change-color-over-time (I plan on doing the same type of thing for the emission on the particles)

Now, the problem is, I want to correlate the particle size with the particle age, but from what I’ve seen there isn’t a way to do this anymore, am I right???
Another problem I’m having is that I want the particles to start in a small space and spread out as they age so that it makes a cone shape effectively.
The final thing that I’m trying to figure out is how to make the fragmented triangles at the end of the trail (See video link above), should I just make a new particle effect that makes smaller ones or is there a way to do something similar in the same particle system?

Here is a link to the Blend file that I am working on: http://pasteall.org/blend/index.php?id=43514

Thanks for the help!