Hi...thanks for the great work you are doing trying to get pets into homes.
Here is a little more information about Manx Syndrome for you: It's a long article, but this site does a nice job with genetic conditions: http://www.messybeast.com/bobtail-cats.html. Here's another good site as well: http://fanciers.com/breed-faqs/manx-faq.html
If this is indeed Manx syndrome (or sacrocaudal dysgenesis), there really isn't much that can be done for the kitten. She will also have the issue. Diapers are an option if she will tolerate them and some owners learn to express the bladders of their cats. Bladder infections and fecal incontinence are also potential problems.
I don't know if she is actually experiencing any pain, but because of her issues, she will likely need someone who is dedicated to understanding her special needs.