(If I may say, it sounds perfectly like CLAMP, having a plot like that! ^.^)

I'm glad that I was able to answer your question in the end!

You're right- no halo because she's a shinki now.

As for illness, it is left up to player discretion. So you are welcome to have her still be weak, or to be perfectly fine. As a shinki, she just won't die (again) from it.