Dear Ms. Rose,
Problem gall bladders can be enormously painful. They take a while, as I understand it, to build up to being a problem, but once they're there, they can be very difficult and very painful indeed. My mother had hers out in the early sixties, when the operation was a very big deal indeed. Now because of improvements in surgical technique, it doesn't have to be such a big deal and the recovery time can be quick.
Because of the effect the gall bladder's had on the patient's digestion and their overall feeling of not-greatness , in a reasonably short period of time, the patient begins to feel better than they did before the operation. I've seen this a couple of times, and this was usually the case. I don't know why your father's having his out, so I can't tell you any more and it may well be beyond what I know anyway, but that's what I've seen.
Kidneys I don't know so much about. Why not have your dad's doctor give you enough information so you can check it out on the internet? Also, it might be helpful if you knew what the diagnosis was instead of simply what they were going to do.
About surgery, it is not uncommon to get a second opinion as to whether the operation is needed and what the cause of the condition may be. If your father is not being seen at a teaching hospital, he owes it to himself to find a nephrologist—a kidney doctor—at a teaching hospital and have that doctor have a look at him. He should take all his lab tests and a copy of his chart and whatever imaging his current folks have taken with him or he may need to have them sent in advance for the consultant to look at. Many insurance plans will pay for a second opinion. If nothing else, they may offer further information for you and your dad and confirm that your dad's current doc is doing great care. The consultant may have options available your current guy hasn't considered or isn't aware of to offer. That's another reason why second opinions can be useful.
Or perhaps your dad's already had one or two. What do I know? I wouldn't dream of telling you not to worry; he's your dad, and you'd have too much sense to pay attention to me anyway. But there's no sense in doing nothing while you worry, is there? Even if you can't get a second opinion, you can get more information and talk with your dad.
I'll be worrying all little bit, too. Let us know how things are going. BobK.