[Zaja]

Is it a heavy script? + How are the loading times of the website affected?
Absolutely not, only added 2,5 kb js. I have seen no slow-down because preview image is dynamically loaded, not preloaded.

Does it work with multi-language stores?
Yes.

Is it possible to show more information, like out of stock etc? Is it easy to customize to display more information?
Not in this moment(except custom job), but we are planning on not only improving the existing functionality but adding new features as well, so stay tuned.

How many files are there to be edited? Easy to install?
Very easy, only 5 files need to be edited(one simple include statement per file).

Does this one works with the TeleFirma Dynamic Image Creator? I've got very large detailed images.
I don't know, I never used TelaFirma image mod.

Will these be resized to a nice resolution?
No, this mod will dynamically load first available Detailed image...in real resolution.

Is it possible to just show a few details? Only info, or only detailed image etc?
Yes..last screenshot above...options setting.