"In touch" simply means to contact someone in some way - by calling them or writing or emailing or even going for a physical visit.
To stay in touch is to continue to write/text/call or otherwise stay in contact with someone.
Someone who has the midas touch has a knack for making money.
I'll get in touch with you later and we'll meet for dinner.
Don't call me, I'll call you
It's not really an idiom. It means "what are you thinking about."
RFP is not an idiom. It's an abbreviation.
It is not an idiom, it means your nose is itching.
It's not an idiom. It means the tip of your nostril.
idiom means expression like a page in a book
"Sieve" is not an idiom. See the related link.
This is not an idiom. It is a measurement. $100,000 is how you write it in numbers.
Simply its mean a bully.