Great stuff Alberto. I've only just noticed your request for colour info on the HVARs - yes, they were Olive Green, and British RPs were Dark Green, with Olive heads. Both the USN and the RN used the light grey on the rocket bodies, and this was also used by most services post WW2, although Green could also be seen in some cases.
The main reason for green was as camouflage, for outdoor storage, so that they would not be as noticeable, from the air, as large piles of light grey things!
Of course, this was not needed aboard ship, so the basic primer coat, light grey, was retained.