1. file times
creation time is when the file got created
modification time is when the file contents last have been modified
and yes that can be before creation time (when file gets copied, as you have experienced).
2. code comments
I would put infile declaration and all actions inside the OK? test
as I said before, JPEG files typically contain a lot of properties, which may be the safest way
to retrieve exposure information. If you want to make sure for your files, just mail me one.