There isn't an idiom here. Spring is a season, and the song is telling how the season is flowing through the air and people can feel it.
The idiom "walk on clouds" means to feel extremely happy or elated, as if one were floating or walking on air. It refers to a state of complete euphoria or bliss.
"Catching a cold" is an idiom - it means to come down with the symptoms of the cold virus.
It is not a spring at all, it is a replacement for a spring. When installed your spring will be removed from the gun and be replaced with a Gas Shock. The firing cycle, sound, and feel is much more solid. Im a huge advocate of gas rams over springs and feel it should be thestandard for all new age air rifles. Springs are old technology. My 2.
Walking on air: to be exuberantly happy, excited, and joyful
It's air because air is everywhere, but it is nowhere to be seen, hence everywhere but nowhere.
It means to rejuvenate, revitalize, or to make something more alive. It is related to the idiom, "A fresh breath of air."
Spring Air Company was created in 1926.
Salt Spring Air was created in 2003.
Hyperbole
For what? Air is everywhere, so, yes.
Everywhere
air is not everywhere, only in a very thin shell over earth's surface