Answering a child support summons, FL?

I am trying to help my brother find out info on answering a child support summons, sorry if this is lengthy. Him and his wife are separated, not divorced, no papers have been filed. She applied for medicaid for their son and the office told her she could not receive it until she petitioned the court for child support. ( THis is according to her) He received a summons with the complaint: stating that she is suing him for child support, retroactive child support for the past 24 months ( the child is 3) the cost of health insurance (even though she wants to use state paid medicaid) The cost of all out of pocket expenses related to medical care. He paid her $500 a month for the first year of separation until he was laid off, after that he has given her half of all money he has received for odd jobs and that was given to him, obviously this was cash. He has no problem paying support but does not want to pay retroactive support and wants shared custody and regular visitation, she has had her phone turned off and he can not get a hold of her most times, she will also not allow him to keep their son during the day while she is at work, no reason other than she doesn't want him too. What needs to be in the answer and should he include all of the visitation stuff and that she won't file divorce papers only because she doesn't want to share custody. Or only to put monetary issues in there. THank you in advance.