Can I shift away from an enemy and then use a move action to get farther away from them without provoking an attack of opportunity?
Yes, if at the end of the shift you are not on a threatened square.
Shift is a move action that lets you move 1 square without provoking opportunity attacks. You can then convert your standard action to a move action in order to walk away your speed.
Note that some creatures may have a reach of 2 squares or more with their basic attacks. These creatures still threaten only adjacent squares unless they also have the Threatening Reach trait.
So long as you are not adjacent to an enemy nor within an enemy's threatening reach, you may move without penalty, even if that move is the result of converting a standard action into a move action.
yes you can. You can use a move action to shift and trade your standard down for a move to take a full movement action.