I feel the same way about DD and the front yard and we live in a fairly quiet neighborhood on a cul-de-sac with a huge side yard but I'm just not comfortable with leaving her outside by herself; maybe when she is 5 or 6.
As for guns, might be Texas but we have a gun too. It is locked in a safe and we never talk about it. I suspect there are a lot of neighbors who have one. When DD is old enough we will explain the gun and DH will take her out to a gun range to shoot one. I feel it is important to discuss it and make the point of the dangers of it all, but certainly for now she will never see it.