Units for (video) files

Hi!

I'm almost about to order Hika Shop Business ...

Now I'm trying to find out if I can adjust the details for my needs.

I wanted to change the Units, but it says

No valid dimension unit entered. The system put back the default units.

How can I change that so I can use it for the data of my files?
Do I have to set up all via the Characteristics or Custom Fields? (Currently trying to figure out how I use this)
It would be great if for downloadable products some information like file date, size, type, etc. is automatically derived during Upload or Import !!!
This would save me a lot time and work to read it from each file myself and type it in.
I'm sure I'm not the only person trying to setup a digital products web-shop. (Especially a good and convenient one with a cart, tax and currency system!)

Thanks for some answers on that,
Jan.