For the noobs:

Idiom: a phrase or expression that is (usually) not taken literally

Euphemism: he substitution of a mild or less negative word or phrase for a harsh or blunt one.

Noob: the uninitiated, so to speak. That is, the newbies. 

The Idioms:

 add colour to: make pleasant

 so to speak: in a manner of speaking

 takes the cake: rank first

 doublespeak: synonym for euphemism, especially when the euphemism is used to mislead

THE EUPHEMISMS:

Paragraph 2:

 sleeping with the devil: doing evil deeds

put to sleep: to kill

sleeping, in the inappropriate sense of the word: to have sex. You know, "sleep with"

fraternizing: the inappropriate sense, again

the Right, the Left: politics

being bull(ie)s on someone else's farmland : invading another country

Paragraph 3: All of the following are related to politics and war

 revenue enhancements: taxes

disinformation: lies

armed intervention: war

liberate: conquer (see why it's a euphemism?)

freedom fighters: rebels (ditto)

enemy: those opposed to our policies

pacified: killed

infrastructure neutralised: infrastructure destroyed

collateral damage: unintended casualities or damage during a military operation

Concentration camps, relocation centres: prison camp for POWs

political unrest: civil war

terrorists: POWs

correctional facilities: prisons

enhanced interrogation techniques : torture methods used on prisoners

Paragraph 4: All of these are related to death

funeral director: undertaker

6inch-by-8inch of fame (this one is my own invention): obituary

The following are all euphemisms for death or the state of being dead: 

going over to the other side

eternal rest

a debt we must all pay

Meeting your maker (for believers, yes)

soundly sleeping

the sweet hereafter

joined the angels

shed our mortal skin

visit Davy Jones' locker

sleeping with the fishes

kick the bucket

go to the big glass house in the sky

Paragraph 5: Related to sex

 carnal knowledge: sexual knowledge

Attempted self-fertilisation: masturbation (colourful expression, eh?)

well-endowed: busty, so to speak

attend the inaugural ball: lose virginity

answer nature's call: pee

All of these mean the act of sex or such:

basic instinct

getting intimate

Hanky-panky (haha)

make whoopee (colourful, eh?)

get busy

sleep around

a bit of the ol' in-and-out

consummating the relationship

making ends meet ("Our profits have declined... we need to make ends meet. Now, now, don't get any ideas...")

Endnote:

saying it by not saying it : well, using a euphemism