No, they don't take up a "whole row". Touchwiz offers a 4x4 layout (just like any other launcher). Your dock doesn't count as a row.
Rooting wouldn't change this either. No devs are currently investing time into tinkering with Touchwiz. It is what it is.
You have no options other than to change launchers. Take it or leave it.
Sent from my rooted/modded/stock Samsung Galaxy SIII using Android Central Forums