This homebrew manages data, ie allow you to import and export save data.
If you accidentally deleted save data from cartridge, but kept a backup, then you can safely restore it.
If you had no backup, and accidentally deleted the cartridge data, then you're screwed.
In order words, the existence of this homebrew doesn't keep you safe. You are in-charge of keeping you safe :3
AFAIK, this homebrew doesn't "dump the entire game". Probably just a different option that leads to the same result, ie the save being dumped.
No clue
I think most Pokémon games don't outright use this? Maybe it is related to battle videos? I don't recall if Battle Videos were stored here (I don't remember how I extracted Zeraora pk file from the video data, nor how I got the data).
There might be other games that use it that may have compatibility with this feature, I don't know.
Keep the JKSM folder safe on your computer, then delete it from your SD card.
The JKSM folder may contain saves that will be useful in the future.
Beyond that, sure, follow the steps in the future