Showing icons over the units

I want to show an icon/bitmap over the squad (or even over a unit) a la Company of Heroes, here are some screenshots:

Here are the icons (the parachute on this case)

The same shot from a different angle, as you can see, the icons are always the same size, and always follow (front to) the camera:


So, I dont now how to begin, initially I have this two problems:
1) how to show that shape, always on front of the camera
2) how to make the shape always on top of a player (or at the center of mass -average distance- , of a group of players)

What would be a good approach to achieving these results?