The idiom "leg up" means to give someone a helping hand or support, usually by providing them with resources, opportunities, or encouragement that they need to succeed. It can also mean to make progress or improve one's position in a particular situation.

The idiom "back the wrong horse" means to support or believe in something that turns out to be false, incorrect or misguided.

The idiom "for a song" means to be very cheap or low-priced, often to the point of being almost free. It can also mean that something is done quickly and easily, without much effort or expense.

The idiom "all hell will let loose" means that something terrible or disastrous is about to happen. It is often used to describe a situation where chaos, disorder, and confusion reign. Example usage:

• The storm was so severe that all hell will let loose if it continues for another hour.

The idiom "white paper" refers to a comprehensive report or research paper that presents detailed information on a topic or issue. It is often used in academic, professional, and business settings to convey complex ideas and recommendations.