I don't know about the others you have on hand, but comfrey is GREAT externally for tissue damage and healing. I've been told not to use it with open wounds because it can cause rapid healing and trap in infection. I would *think* a surgical wound would be fairly sterile...but just a word of caution there.
I've personally used it (dried, chopped herbal grade) for pulled hamstrings that had given me days of severe pain. I sprinkled it on a warm, wetted towel, then applied directly to my hamstring areas. I placed a dry towel on the outside of that and then a heating pad (Because of it being the back of my thighs, I sat on all this on the couch, so really I did it backwards, so the heat would radiate up through the towels and comfrey.
My husband made some recently into a solution and mixed it with DMSO (a horse linament, but an excellent absorbing carrier oil/solvent basically). That's a bit more complicated...You make a fairly heavy comfrey tea, allow it to cool, strain it, mix it with the DMSO. That creates an exothermic reaction, so you have to allow it to cool. Once it does, it's ready for use/storage in a jar. Just rub it on the effected area.
You didn't mention it, but tobacco is supposed to have almost the same soft-tissue effects in case you have that (Use in basically the same way).
As far as liver protection, Milk Thistle is a good one specifically for that (I've also taken it for that reason, but just bought herbal capsules). Dandelion root is supposedly amazing for it, too, but no personal experience there.
Best of luck to him!