She's hissing bc she's saying "go away", so if she bites you it'll only be a tag. She'll bite and let go before you can even blink It's happened to me once with someone else's young bp, you'll be more startled than anything. It doesn't hurt at all and she won't hurt herself, don't worry.

I wouldn't move her to a tub to feed. I did this at first years ago and it ends up being a hassle. The last thing you want to do is handle your snake after they've eaten, so just feed in the tub. To be honest I would wait another week before trying to feed. She already sounds stressed out and you'll probably end up wasting the rat if you try now.

(By the way, you still have to post pics )