I've not ventured into the realm of whole prey, but I do agree with checking for parasites and leaving out the intestines for the same reason.
I prefer to feed whole parts and let the cat decide for themselves what they can handle. I do this with the bone-in chicken that I feed. When it comes to the
thigh wing drumette bones, there is always a bit from the center that's been left, though it's been thoroughly scraped clean of meat and the ends have been chomped up. There is a very obvious dental benefit to even scraping the meat off the bones. Also, the ligaments on the whole pieces kind of act like dental floss. lol.
As for the fur (or feathers), I've seen it postulated that they are the "fiber" in a diet that contains no plant fibers, and that it is beneficial for preventing hairballs. I dunno... seems odd to me that if a cat can't digest their own fur, why would the addition of prey fur help the situation?... not sure how that works.
As for the low-taurine issue in rabbit, I've seen that before as well. Yet, it's odd that many feral/wild cats do choose rabbit as their primary prey and thrive on it. I think "primary" is the operative word; primary does not mean
only. I'm sure that they are still eating other small prey on the days that they can't pin down a rabbit. As always,
variety is the key. And if you can't get much variety, then by all means supplement, either with some extra heart meat or with vitamins.