Obtaining Legal Custody

So, I'm not sure how to go about this.......................

I have a five year old child from a previous relationship. I'm now married & have been with my husband for three years. My son's father lives a five hour flight away & sees him rarely. He is not the most responsible person & drifts in & out of employment. I've been raising & providing for my son since birth. I want to make it official by seeking legal primary custody. I have no intention of asking for child support as I know I wouldn't get it. But how will our situation change if I do this? What sort of visitation will my ex be entitled to? I've never prevented my son from seeing or talking to his father, but we've always done so when practical. We live more than 1,000 miles apart. Will I be required to make arrangements for more regular visits? Will the state try to force the support issue? And what will this cost me? I don't want to put this off simply because I can't afford it. Are there attorneys who can help? This is all new to me, so I'm really at a loss. Any advice would be appreciated.

You two can agree whatever visitation you would like. If you cannot agree the court will give him some time and you will have to obey the order.
Might it be fine as is? What problem has been caused?