As part of the Envisage 365 project, I take LOTS of pictures. I try to take pictures of everything - mundane, funny, interesting, or simply there when I need to take a picture.
5. No - it can never take the place of a parent/child dialog - as this is where we initially gain all of our cultural clues as to How to communicate to another person. Our very survival depends on being competent at communicating with that primary adult. Now, children in child care have to expand or change some of their coping skills in order to be able to communicate with new adults effectively. I don't think this gives an advantage or disadvantage to the child - it simply is what it is and children are really resilient.
Does is differ between girls and boys? Usually - yes. But not in a dramatic cognitive way - by that I mean that it will differ in content the same way that boys and girls solve problems, which does have some socialized gender based tendencies but rests - I think- more in base personality style. Some of this has to do with gender based differences in our brain development, which is another thing that we have no control over or about.
Officially, it isn't a two way dialogue. BUT ( and here is where the basis of my dissertation rests) - I think it IS a way to broadcast information to peers. Both Vygotsky AND Piaget said that it was only cognitive in nature, whereas I posit that it is also social - it HAS to be social. In fact I think it is the way that children assist each other in the difficult and long journey of learning to communicate with a wide variety of people. I think they drop this when they have gained enough skill as communicators and thinkers to be able to do it without this "scaffold" from one another. And Yes, they are documented to do this much, much more when they are with other people - children in particular. When they isolate in lab situations, children don't self talk nearly at all....which is another reason I think that it has an important social function.