1. Is there a Night/Day cycle?
Nope, think it's possible that it will be added later.
3. Do characters need to eat? (Or maybe food is used like potions?)
Nope, they don't
need to. But there's lots of benefits to it and lots of food to craft.
4. What is the maximum level reachable?
Even with missing a few quests and not killing all enemies, I hit level 21. Level 20 is recommended to be at when finishing the game.
5. Do enemies respawn? (or certain generic enemies)
None of them respawn.
6. Do Ingredients respawn? (like plants collected)
None of them respawn, but they can be easily acquired through merchants.
7. It is possible return to zones already explored? (for example Cyseal). And it would be useful return?
You can definitely revisit Cyseal, there is only one zone which I know of which you can't return to, and it's a dungeon which is part of the zone you go to around halfway through the game.
8. Which kind of objet can I toss/sold safety? Ones say 都ell it? but others like books of recipes already learned?
Sure, sell the ones which say sell it. There's also things like chalices, paintings, cups which you should sell. Basically, keep every item if you know it's useful (or don't know if it's not useful, especially ingredients). Books and treasure maps are okay to sell back once you learn their recipes/secrets. Don't sell the diaries and journals or notes though, they'll be helpful or perhaps required for quests and you'll have to track back and find the NPC you sold important items to.
9. Is there a complete wiki for this game? (I know few wikis but all of them are pretty empty)
There's a lot of content, most people don't have time to spend very long amounts contributing to wikis when they just want to play. So there wouldn't be a complete wiki by now.
10. Finally the most expected: Is there a modders comunity like Nexus mods where find mods well ranked easily?
A nexus page will probably come up (or probably already has), there's also the Steam Workshop.
I'm not sure about the real time/game time scale.
