Adopting Stepchild in Ohio - Just Getting Started

Hello, I recently got engaged to my girlfriend and we're planning to get married in November of this year. We're both residents of Ohio, and she has a 6 year old son that I'm planning to adopt after we're married. I have a great relationship with the child, and he thinks of me as his father (he's been calling me daddy for over 2 years). I support both of them, and we have a very nice, loving and caring home. Some background - the biological father is not in the picture and hasn't been in 5 years. Absolutely no contact what-so-ever, not one red penny paid in child support (although it might be necessary to note that child support was never formally or legally requested - I'm not sure if that matters or not). He and my now fiance split shortly after the child was born and that was the end of it. She decided that it would be better to leave it be and not go after him for anything - a decision I agree with. He is a bad seed, with a history of drug and legal problems, including violent offenses and theft. He is not a responsible parent in any way, shape or form, and in fact has documented on his social networking profiles that he does not want kids. Here are my questions: -Do I need to bring the father back into the picture after 5 years of clear abandonment, or can I do this on my own? -Should I hire a lawyer? -What is the average cost for adoption for my situation in Ohio? I'm perfectly willing to pay for court fees, lawyers, whatever is needed, but only if I need to based on my situation. -What are my next steps? I'd appreciate any help any of you can provide. I have several friends that are lawyers in my area and they can help point me to a good DR lawyer if I need to go down that path. Thanks everyone.