a) The first part wasn’t meant to be literal, it was a hypothetical taken from the assumption of your belief and contrasting it to fact.
b) I wouldn’t call a God that allows people to suffer, through no fault of their own with such diseases like cystic fibrosis, good. You can dress it up through arguments about original sin, but at the end of the day, your god would be allowing innocent people to suffer because of the actions of others previously. That is not good, it is psychotic. Your acknowledgment that your god is all powerful shows that you know that it can stop this suffering, but chooses not to. Remember, people with inherited conditions get such without any kind of moral choice, so cannot be taken as punishment for immoral life decisions. Anything which would choose to put that on people is sick.
I don’t believe that this is a purposeful decision of anything, because I don’t believe in a creator, I am just pointing out that this wouldn’t be the action of a loving god. The alternative is that God isn’t all powerful.