In Arizona, there is no longer a requirement for an individual to obtain a CC permit. However, there are certain restrictions that apply to non-permit holders as opposed to those that have taken the CCW class and have a permit.
An example - I took the CCW class last winter here in AZ. As a permit holder, I can carry in to a bar, BUT, I cannot drink. Someone who CC but does not have a permit, CANNOT carry in to a bar.
As far as the qualifications that you are questioning - age, eyesight, etc. For the class, we had 8 hours of instruction - mainly reviewing laws, etc. and then we had to "qualify" at the range. We each had to fire about 50 rounds. If you had problems with hitting the target - the instructors worked with you. Some did not have their own weapon, etc. Inl the class of about 35 to 40, I would say the average age was between 55 to 65. AZ is a "retirement" state after all. Personally, I am a diabetic, I do have some vision problems due to past laser treatment but I have no problems in shooting both pistol and rifle. I do not consider myself a "crack shot" but with the instructor watching over my shoulder as I qualified, she made the remark that if she ever got in to a gun fight, she hoped that I would be there to back her up. The applications for the CCW ask the usual - DOB, physical description, etc. The application is sent in to the Dept. of Public Safety which runs a criminal background check along with our fingerprints which were taken by one of the instructors. I was surprised as I received my permit card - good for I believe 5 years at which time it can be renewed by mail, within a week. The instructors were very helpful to those that had some difficulty in their marksmanship and spent extra time with them. At the end of the class, no one failed.
To address your one question - as to when you know it is time not to carry. In my case, I'm 60. I don't feel comfortable about just sending money in in another five years and getting an automatic renewal. Not that I question myself but because laws change and you need to keep current. I will probably take the CCW class every couple of years just to keep up with the laws, etc. I am partially deaf in one ear, have some vision problems but can still drive and practice shooting frequently. Practice, practice and more practice is part of the secret to being competent. I am of sound mind as well. As far as "when" should a person stop carrying? I honestly believe that each person has to decide that for themselves but when it is time, you will just know. In the winter, I'm about 45 miles north of the border. You would be surprised how many "elderly" gentlemen I see carrying - many times open carrying. I'm talking gentlemen who are in their mid to late 80s. After all, if they are mentally sharp and practice shooting (which I'm sure many do) and are physically able to get around and drive, why shouldn't they? After all, the elderly are the most vulnerable for being victims of crime.
Your post is a good one with some very valid questions/observations.