1. Display each icon as 1 line (small icon and caption) in a fence.
Do you mean like in the Details view of Windwos explorer?
Also, you can hold the Ctrl key down and spin your mouse wheel to adjust the size of desktop icons.
2. Change z-order between a fence and a fence.
The last fence you select will be on top. Having said that, Fences was not intended to have significant overlap.