WE ENDOWED THEE WITH NUMEROUS FAVORS!
VERSES NO.1-8 
The favor of expansion of breast here implies openness and breadth of Prophet's mind and spirit by divine light and heavenly peace and tranquility. It could include Prophet's breadth of knowledge through inspiration and mission, as well as increase of his tolerance, patience and resistance against the enemies'obstinacy and hindrances.
It was thanks to this expansion of breast that Prophet (SA) could pass the difficulties of messengership in the best way and accomplish his tasks well. The burden here refers to the difficulties of messengership, prophethood and invitation to monotheism, and elimination of appearances of corruption from the tainted environment. Not only Islam Prophet (SA), but also all prophets faced with such great hardships at the beginning of their invitation. It was only divine support that they could overcome such problems.
Your name and fame has spread everywhere besides the name of Islam and Quran. Testimony to your messengership is besides testimony to monotheism and unity of Allah, and is a requisite for acceptance of this religion.
Don't worry and despair not! The difficulties and hardship do not endure, the enemies' hindrances do not continue, and Moslems' material weakness, economic problems and poverty do not continue. 
The above two verses are in the form of a general ruling giving the sincere and laborious believers the good tidings that there is always relief with every difficulty. Patience and triumph are two old friends, and the former is followed by the latter. 
However, one shall always turn to Him, and seek His pleasure and satisfaction. 

THE END OF THE EXPANTION SUREH