1 - I will not tie file corruption to a product or a specific release. While i have seen some (but very little in total) file corruption in 2017, i have seen it in previous releases too. It's almost never a general error, and the source of the error can be very tricky to find.
I recommend you set up a test system. Import files, run file version upgrade, test.
2 - When checked into PDM, the file will get an ID in the database and this ID will never change. It's the ID PDM uses when processing the file, and it doesn't have anything to do with name or location. Meaning you can rename and move files between folders as you please.