Object hair particles orientation

object hair particles need a very specific settings to be able to follow surface deformation. I spend hours to figure out how to do this...
Enable Advanced settings, velocity to tangent, not normal, rotation to velocity/hair and angular velocity set to velocity .
Then, your hair mesh keep their orientation along the surface normal.

 

Athmosphere setup

Example photography of athmosphere effect:

 

Problem: How to render "fog" with no sky alteration?

First render:

  

Select all scene objects then set pass index to one (Alt to apply to all)

 

in layer passes :

 

compositing setup:

result:

 

>>download the scene