Keeping metadata (time/date) when extracting frames from video
If you are saving frames from PP using the snapshot tool, then by default it's saving a file that's of the form SEQUENCENAME_TIMECODE.  If you know the date/time of the start of the sequence, you can compute frame-accurate metadata by adding the timecode of the image to the adjusted datetime of the sequence start.  (By adjusted datetime, I mean that if your sequence starts at 01:00:00:00 and your actual clip was 16:20:25:15 on Apr 1, 2014, then you need to subtract one hour from the clip time to account for the SMPTE offset).

As for programming languages that will do what you want, look at bash (the Bourne Again Shell), Python, and/or Perl.  Perl is wicked cool in how it can slice and dice strings, do math, and put the strings back together.  But it is also wicked hard to learn idiomatically.  Python may be the best starting point.

EXIFtool is a great way to embed correct metadata into image files: http://www.sno.phy.queensu.ca/~phil/exiftool/

And it's a way to learn some Perl while you are at it.