And what was the purpose of the officers?
Ramban and Rashbam: To collect the produce throughout the land (for storing away during the bountiful years), since it would not be possible for the viceroy to do it himself.
Rashbam (on Pasuk 35): The officers were needed to enforce the law, since the people would not be willing to go along with it.
Moshav Zekenim: Yosef said to appoint overseers (plural), so if he would not be the head, at least he would be one of them.
What is the significance of the opening words "Ya'aseh Pharaoh"?
Seforno: The king should appoint officers in each and every town, so that they should acknowledge the viceroy as their head and as such, they are obligated to follow his instructions.
What is the meaning of the word "ve'Chimesh"?