as I understand it hasn't been updated much recently (I could be wrong)
You are.The latest stable release is 2.6.11 on October 4th. It's one of the GNU flagship products and is in continuous development.
No, nor does it support 16 bit processingI stand corrected.
Does Gimp support RAW?
I believe theres several different versions of "gimp" some with a more photoshop like interface (gimpshop?) what the connections with the original are I have no idea.