Focal length is focal length. It is a property of the lens, not the camera.
A lens focuses light at a certain point (the film/sensor plane of the camera). It projects this light as a circle (the image circle).
Most cameras have sensors that are rectangular. To maximise your imaging you need a sensor that is smaller than this image circle. Imagine for 35mm/full frame format, a rectangle that has its points close to or on the line of the circle. Now draw a smaller rectangle inside your larger rectangle. This is the relationship between larger and smaller sensors, and why it is referred to as crop-factor - you are literally cropping the image supplied by the lens by using a smaller sensor. The physical properties of the lens remains the same (aperture, focal length etc) regardless of sensor used.
Where people get hung up is equivalency. If you want to use a lens on a smaller format to mimic the appearance of an image taken with a larger format, then you have to do the math for focal length and depth of field.
irfanview has and probably always be one of the most simple yet powerful tools for photo work that people don’t seem to know about.
I just had a quick look and what you want may be possible. Q: How to use Batch conversion/rename to sort result pictures in folders with date-taken in folder name?
A: In the Batch dialog, you can use Placeholders in the name of the output directory. If you set a directory name like “C:\sorted images\$E36868(%Y_%m_%d)\”, you will save the result files in folders with date-taken (format: YYYY_MM_DD) in folder name, like “C:\sorted images\2011_06_23\”.