Frozen to the marrow is very cold.

In cold blood means with malice aforethought or deliberately.

Sang-froid is French for cold blood.  In English it is used to mean cool, calm and collected.

I’ll have your guts for garters is a popular threat.  Garters are usually made of elastic and used to stop socks falling down.

Back-biting is speaking ill of someone, presumably behind their back.

You are making a rod for you own back.
This saying is about making unnecessary work for oneself.  The rod in the saying would have been used to beat someone as a punishment.

Back to back describes a way of building houses for workers in Victorian times.  Dosá-dos is the French version, which describes a move in dancing.

Skin and bones describes a vey thin person or animal.

No-one wants to hug a bag of bones is a saying which overweight people are more likely to use than thin ones!

Lend a hand is the Brownie motto which I learned as a child.  It means to give practical help.

Eating out of her hand means tamed to her will.

Dig your toes in means resist.

Hightail it is American slang for moving at high speed.

John 1:14 explains that the Son of God became flesh.