Hi A.,
I'm gonna start by saying I have never breastfed any of my children and I have 4. That being said here is my advice...
First off it is totally your friends choice to start weaning him from breast feeding. But there are a couple of different things that need to be addressed before this can happen.
Here are the issues that you have mentioned ~
* He is biting
* She co-sleeps with him
* comforts him with breastfeeding.
* in addtion she still has to get him of the bottle.
Your friend needs to decide what she wants to happen in each of these areas.
Advice...
With the biting I agree with the other ladies that have said tell him no and no bite, in a stern voice and then put him on the floor for a few minutes.
So she doesn't have the heart to put him in his own room, own bed well there has been no child being mistreated because their parent makes them sleep in their own bed. I personally wouldn't be able to sleep if I had my 5 1/2 month old daughter sleeping next to me, I would wake up at every sound she made or movement. So here again her choice, how to get started if she does (first she is gonna have to pick which battle she wants to take on first) I would start with his naps at home and he sleeps in his room, in his bed.
As far as the comfort nursing I would imagine at this point he would not take the pacifier and if he would he may become attached to it, but with the pacifier you can control the amount of time he uses it. And by this I mean he is only givin it when he wants to soothe himself or is reading to go down for nap or to bed for the night. Also other options rather than offering the boob or pacifier would be the bottle or a sippy cup with water, juice, formula or breast milk in it.
In my opion you probably shouldn't replace one with another and if you are gonna wean him do it all so you don't have to do it again.
She could do these things in phases start with the biting and the going to bed on his own, comfort nursing could be replaced with a sippy cup.
But also it would not be a good idea to start the habit of him taking a sippy cup to bed, you will have to stop anyway sooner or later.
hope this helps W.