Click to move enables you to use click movement as opposed to wasd or arrow keys. Basically, you click an area on the ground and your toon moves there. You need to use this in conjunction with Interact with Target on slaves, as it allows your slaves to move independently to get in range to interact.

For example, you target something 20 yards away and tell your slaves to interact with it. If Click to move is off, they will stand there and say "Too far away". With Click to move on, they will essentially click the area at that target and move to it, then interact with it, either via opening dialogue or autoattacking, or even skinning or looting.

There are many ways to use interact with target for melee toons. Most use a multi-step configuration in ISBoxer. I use it manually, tying my melee interact with target to my tab key where my master has a targetting + macro.