DollyDo,
I wanted to answer your question about my son living with his dad.
His dad loves him. He's a good guy, and we get along well, for an ex-couple. We've always put our kid first, and we even spend holidays together.
But his dad isn't up to the challenging task of caring for a teenager. One, he works a service job with constantly changing hours--he would never be home with my son, especially at night. Two, dad has ADD--without the H. Three, his dad doesn't have much in the way of income--he makes, literally, poverty-level wages. Fourth, his dad lives, as my son puts it, "in the ghetto." Lots of drugs and ample opportunity to spend long hours with other troubled kids, without his dad around because he has to work.
Although my son and I have a challenging relationship, it's best that he live with me, especially since he's made some solid program connections here. That said, if the above were different, I'd send him to his dad in a heartbeat, because he is too dependent on me and needs a strong male role model. As much as my ex loves his son, he cannot be that role model.
Thank goodness he has a loving sponsor. This dude is as opposite of me as you can get--former Special Forces, politically conservative, etc.--but he is a wonderful guy and my son is just soaking up his ESH and attention, which my husband is unable to give (although he absolutely loves my son--in his own way).