Smithie, I'm concerned that you're going to be disappointed, or even worse, hurt badly, by *hoping* for zero contact, for complete closure. I totally (seriously, I do) understand wanting to distance yourself, and your child, from his/her birth family. But, no matter how hard you try, or to what extent you believe yourself to be separated, I believe that's a falsehood and an impossibility. Your child will never be completely separated. And, neither will you. You could move to Antarctica, with no internet services, but the reality of adoption will exist in your lives. And, if you're trying to deny that, or in some way sublimate it, it will likely, as most things do, become even more central to your, and your child's identity.
I don't have a good relationship with my daughter's birth mother. It's not all wine and roses by any stretch of the imagination. And I DO severely restrict, to the extent that I'm able without becoming a totally emotionally obsessed woman, photographs in particular on Facebook. But, at the same time, that stuff is out there, and I'm a somewhat public person because I write about my daughter, and am published doing so. I've come to the conclusion that I want my daughter, and her birth mother for that matter, to have the record of me working out my own identity, part of which is that of an adoptive mom (who dealt with years of infertility), because that will model how I hope she can learn to work out her own, flawed and bruised and scarred and lovely and amazing, identity, part of which is/will be an adopted child.
Are there boogiemen/women out there? Of course. Are there dangerous birth parents out there? Of course. But, it seems to me, that "protecting" my child (though in reality this seems like a more personal protection, rather than the child's protection) is best done by showing her how to navigate the dangerous world, not run from it.