QLD Family Court Proceedings - Will Domestic Violence Order Impact Results?

Hi,
I was wondering if anyone has had experience with DVO's in family court proceedings, mainly parenting orders.

My ex husband has acquired Legal Aid for mediation to have contact with our 3 year old son. This will occur in 2 weeks time. He has had a police Domestic Violence Order against him for about 2 years now (it was extended until the end of this year) in which he cannot come within 100m of my son or I, locate where we live, communicate with us in anyway etc. He has been charged twice for breaching the Domestic Violence Order, but only for minor things such as posting comments about me on Facebook. Unfortunately the police could not prove the other major breaches so they didn't prosecute those.

It is not safe for my son to be unsupervised with my ex as he has mental health/drug issues and amongst other things, burnt the soles of my son's feet with a heat massage when he was 9 months old, tackled me while I was nursing him causing both my son and I injury when he was 12 months old, trashed his playearoom while he was in it and held a butchers knife to his wrists threatening to kill himself in front of my son. He also threatened to kill both my son and me if I ever tried to leave him. He said he would track me down and slit my throat and I better have two graves ready for my son and myself.

My question, if I don't give my consent to my ex contacting our son and/or visiting him, and this matter goes to court, how much weight will the Domestic Violence Order have? Also he has a $2800 child support debt. Will this impact the magistrate's view?

I am trying everything to protect my son so just trying to get as much information as I can.