No New content, this is just the release of the "Official" English version done by Kagura Games
New Events and story featuring the guildgirls
personal preference on which to download. as for which Mods are good, Daseson's Colour Mod does just that, adds colour to the game. FFFox Mod adds Quality of life features and Kitsune sister, with a few extras.
No, neither version has any DLC because the DLC has not been released yet.
It is pre-patched with Kagura's "NSFW" mod, which restores content cut so it could be released on Steam.
It's the same game, Kagura for reasons known to them renamed it.
That comes down to personal preference.
There is a Mod (Dasesons) that adds colour to the game.
I know, oh god do I know.
I'm off to play Eternum for now, I'll add the money fix to the OP first though.