A casual way of saying to friends I'll see you again, sometime, (without a definite date or time having been set) - this is often abbreviated to 'Later' or 'Laters' as an alternative way of saying goodbye.
If a person sells their birthright for a mess of pottage, they accept some trivial financial or other gain, but lose something much more important.
'Sell your soul for a mess of pottage' is an alternative form.
This is an old biblical idiom but still used. It refers to the lees (dregs, sediments) of wine or other liquids that settle in the bottom of the containing vessel if it is not disturbed. Hence, the idiom refers to someone or something that is at ease, not disturbed, or worried. Sometimes this also has reference to a false assurance.
Shades of meaning is a phrase used to describe the small, subtle differences in meaning between similar words or phrases; 'kid' and 'youth' both refer to young people, but carry differing views and ideas about young people.