The Relief from Distress : An Explanation to the Dua of Yunus (Ibn Taymiyyah)

Shaykh al-Islam Ibn Taymiyyah, may Allah sanctify his soul, was asked about the saying of the Prophet (pbuh),

The invocation of my brother Yunus, none has the right to be worshipped save You; glory be to You, far removed are You from any imperfection; I have been amongst the wrong-doers, none who is experiencing difficulty employs it except that Allah would relieve him of his difficulty.

What is the meaning of this dua (prayer, supplication)?
Are their any unstated conditions that have to be met when one articulates it?
What is the connection between belief in the heart and the meaning of this supplication such that it leads to the removal of difficulty?
Why did he explicitly confess, I have been amongst the wrong-doers when it is known that tawhid in itself leads to the removal of difficulty?
Is it sufficient to acknowledge ones sin alone, or must this be accompanied by repentance and the firm resolve not to repeat that sin in the future?
Why is it that difficulty and harm is removed only when a person relinquishes any hope, reliance and dependency upon the creation?
How can the heart relinquish the characteristic of putting hope in the creation and depending on them, and instead put its hope in Allah, Exalted is He, and turn to Him in its entirety?
What are the methods that would aid the heart in doing this?
The author replies to these questions in the form of this book.