Looking for more behind the scenes information

I'm really curious as to why you were never able to see Jacob Marley or the spirits, except for the Ghost of Christmas Present. I also couldn't understand why we never got to see Scrooge as a little boy, Fan was omitted, Fezziwig was omitted, we never saw Scrooge as a young man before he became mean, we never got to see Scrooge meet and fall in love with Belle. Hicks has dyed hair in one scene with Belle leaving him because of the way he is, but it's flat because that moment is never set up. If anyone can help me find where I can find more information on the making of this film, I would greatly appreciate it.