Hi!
I don't know how common it is, particularly if you're like me and you don't speak Spanish very well! I was in contact with the foster family via telephone and via e-mail for the wait between my visit and pick-up trips. I only called once, I think. Because of the language barrier (no one in the foster family speaks English well and, as I said, my Spanish is pretty marginal), the call was short and kind of awkward. I got to speak to Gabriel, but he didn't speak back. Now that I'm home, I see that's pretty typical with him. He's fascinated by the phone and when you put it up to his ear to hear someone he knows, he smiles really broadly and then tries to play with the buttons.
I'm not sure how common it is for foster families to have computer access. Gabriel's family did, I think, in part, because the foster father and two of the foster brothers all work in the computer industry! The foster Mom and I e-mailed each other about once a week, once every other week. In one of my first e-mails I asked for a real description of how Gabriel and the foster Mom spent their day -- from when he got up to when he went to sleep. I also asked for detailed information about the foster family, so that I'd have that to share with Gabriel when he gets older. At my request, they took lots and lots of photos of themselves with and without Gabriel.
I spent some time with the foster family when I went to pick up Gabriel, which was so great. We talked about all sorts of things. I felt so lucky to have some time to really get to know them a bit.
Hope this helps!