Hi. I'm a newbie on this forum, used to be a readonly member. But today I need few advices from advanced CG artists, if they don't mind to help me

I have a simple nParticle simulation. It creates an asteroid field. I've used this video
tutorial as a reference: https://www.youtube.com/watch?v=ZKR0_JroHfI
Thanks to its author, I know about expressions a little bit more than nothing.
I have an idea to emit new particles from existing emmiter.
The first problem is that I can't make the new particles to inherit velocity from first
emmiter.
The second problem/question - is there any chance to tweak those particle shapes a little bit to make tails wider at the start of their life and thinner at the end?

Thanks!

here is a scene example Maya 2012 binary.

Visual representation is in attached image.