Transferring items between Diablo characters?

[Rudra]

your item pool is backed up to your computer [...] while the stash is within the game itself only.

Hi, this is definitely not the case.
The plugulmo.ini allows you to determine the exact name of the stashfile, which will be generated in your Diablo folder and contains all of your items then. Afaik it's "Diablo_MP.st" preset.

If you backup this file, you backup all of your items.