Slitherine

Is there a way to slow down the enemies moves? They move so quickly and skip around the map so much that I have a hard time seeing what they are doing. More specifically, a way to slow them down on an iPad....

Or, failing that, is it possible to get a list of the oppositions moves?

Also, what are the conditions that force a unit to retreat?

Surrender is a function of entrenchment, suppression and freedom of movement.
A unit will retreat if after a direct attack (so not artillery, air or naval attack) it has 0 remaining entrenchment. If it has nowhere to move to, then it surrenders.
Since an attack removes one entrenchment, the target can have 1 or 0 entrenchment before the attack.
Your attack will usually kill some strength and cause suppression so you don't have to have the unit fully suppressed when you attack, although this is a good idea for a heavily armoured unit, especially for an expensive and powerful unit worth a lot of prestige (you get half the remaining value when it surrenders) and it's in your interest to ensure you get rid of it quickly.
Understanding what units can move into what terrain is useful as this means you only need to place units in hexes the unit could move to.

I can't help with the enemy moves. I think there's a command on the PC version that alters the displayed movement speed, but I don't have an ipad so can't comment there.

In the PC-Version it is possible to change the movement speed via settings (Menu). Maybe it is the same with the IPad? If you don't have such a slider there, I am afraid there won't be an option.