How do Ferrets Communicate?

I am pretty convinced that there is some sort of communication between ferrets.  I did some reading and they do have 2 primary modes of communicating with each other - vocal and body language.  I have a couple of examples of the communication we see around here.

First let's start with the girls.  Violet and Madison chat frequently.  They climb up on our bed and get under the covers and then they start to gossip.  You can hear that Madison makes some noises very similar to dooking (the happy noise a ferret makes). You can tell its her because she is smaller and has a higher pitched voice.  Then Violet responds with a lower pitched set of the same type of vocalizations. Back and forth the go - its quite sweet.  They remind me of 2 teenage girls at a slumber party.

The boys - Finnegan and Theo.  Not sure what type of communication they were using but the were definitely in cahoots.  It was time to change the bottle in the water machine - resulting in an empty five gallon water jug in the kitchen.  Theo and Finn were fascinated with the bottle and managed to tip it on its side.  After a few minutes of sticking their heads in the opening they decided it was important to hoard the water bottle.  The location they picked was the hutch in the dining room.  Finn grabbed the opening of the bottle and dragged it from the kitchen, through the living room and entry and into the dining room.  He proceeded to go in through the back of the hutch and push on the door to make it open.  He was standing in the hutch with the bottle in his mouth pulling with all his might and Theo was standing with the side of his body pressed up against the bottom of the bottle pushing to help get it in the door.  Of course the plan was flawed all along because the giant 5 gallon bottle wouldn't fit in the hutch no matter how hard they tried.  It was an interesting demonstration of them working together though.

I wish sometimes that they could communicate with me - tell me if they aren't feeling great, etc.  I guess I will have to settle for knowing they have each other to "chat" with....