Walking on air: to be exuberantly happy, excited, and joyful
Yes, because you cannot literally walk on air.
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.
Knows something about everything
Someone getting their walking papers is just like getting "the pink slip". It means he or she has received his/her notice of termination (the "walking papers" or "pink slip") and is no longer of the company.The idiom of "getting walking papers" has been extended beyond the workplace and into other social situations: in which case it generally means the recipient is being told to get lost and don't come back. For example, a girlfriend dumping a cheating boyfriend can be said to be "giving him his walking papers".
Picture someone holding their nose up in the air - they look very aloof and snobbish, right? That's what this idiom means.
It is not an idiom, it means your nose is itching.
It's not really an idiom. It means "what are you thinking about."
RFP is not an idiom. It's an abbreviation.
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.
This isn't slang or idiom - it can mean either literally filling up a suit, as with a body or air; or it can refer to the legal term of a suit as in a lawsuit.
"Sieve" is not an idiom. See the related link.
It's not an idiom. It means the tip of your nostril.