Legal Guardianship?

I posted our story on the general foster support board, but thought I might get more specific answers here, since we live in IN. :-)Our foster kids went back home about 12 days ago and the youngest one- FS 2yo- is having a very rough time. His mom is unkind, unfair and (I suspect) abusive to him because he is caucasian while the other children are AA. They call him names to ridicule his race. He is a darling, sweet child with blonde curly hair.We've had these kids for 21 months, FS was only 8 months old when placed with us. He has completely bonded to us and is grieving his loss. He is sad, downcast and lonely. I've seen him twice in the past 12 days and both times he's been covered with flea bites and/or lots of bumps and bruises. His eczema is not being treated, so those patches are bleeding.He looks completely pathetic and my heart is totally broken in pieces.DCS hasn't even cared enough to make sure pop-ins have been happening. In fact, no one besides me had even checked on the kids in all that time.I've reported everything I've seen and it's been landing on deaf ears at DCS. Until yesterday. I got CASA involved and they are fighting to change DCS's mind.This morning, it was decided that the CASA director and the DCS supervisor are going to ask the mom to give guardianship of FS to us!We're praying she agrees to this. It would be wonderful to bring this precious child home and fill his lonely little sad heart with all the loves and hugs and kisses it could hold.My questions are: How is this different from adoption? Can we change his last name to ours? Can we change his SS# to protect his identity? Will his mom be able to take him several months or years from now? Will we have say-so in how often she is allowed to see him? (We really want to put space and time between her and this child to give him time to heal emotionally from the hurt she's caused him.)Thank you in advance for your input!