In general, playing the tank or healer is easier then playing the DPS toons.

The tank will frequently want to move to pick up an add, or to position or face the mob away from the team.
If you're not playing a tank, the healer generally is the most involved.

Ranged DPS are the easiest to deal with, because they sit there and DPS away, usually on a macro or two.

With the new "Click to Move" and "Interact With Target", melee can be controlled much more easily.
You could have the feral assist the warlock for target, Interact with Target, and spam a dps macro.
For leveling say as a Cat, this could work well, but if you decide to tank as a Bear, likely you'd want to control the Druid as the master.






I'd personally control the druid in this set up.
Have the warlock as the slave, break follow and away you go.

I'd personally have the druid as cat for most content.
Things will die very quickly outside of instances.

If your lock is Felguard spec (50+), two points in Improved Health Funnel and the glyph for Funnel...
And a Felguard can tank 5-man group quests quite easily.
Druid could kitty dps for low threat and heal the warlock when needed.
If you're not Felguard, Bear form with lock dps will do any two man quests easily.