[RPG] How much should characters know about encountered creatures in 4e

I like to work like this: I give the basic information to the players. One single page of 8.5 x 11 with all the info they certainly know. I tell them everything that is outstanding. How many moons, color of the sky, name of the main constellations if they are relevant. Any info about the basic religion, main genesis myth everything relevant for the first adventure and their basic character creation. This page is info that even a farmer knows.

Then I let them create their characters and ask me all the questions they want. I keep note of my answers in a form of a Q&A by email (or my own private website for my group).

This method works for both Homebrew settings and really odd settings.

I make sure the first adventures are introductory to the tone of the setting and the campaign so they know what's going on. I once started a campaign by a paladin executing a child in public for stealing food from the Temple. I wanted the players to understand that in my setting, alignments are more complicated than they look.

My biggest piece of advice would be: Don't take all the job on your shoulders. This is obviously optional, but if you create the broad strokes for a game setting and you say something like: Elves are the dominant race in a world of floating islands, humans are haunted for their skins and orcs are invading the world from the moon with their army of jetpack wearing soldiers. That's all good. But leave it like that. When questions arise about the world, turn the question back to the players and use their answer. Build the world with them. When you know something and you're sure about your answer and how to portray the world, just do it. But in doubt, turn the question to the players. Their character will certainly know better.

Alignment Usually Isn't Hard To Determine

Alignment often isn't that hard to figure out anyway. Spells that can detect it are readily available, some classes (like Paladins) can detect evil as much as they want, and in certain cases you can discern it from their actions (a Cleric casting a Good spell can't be evil, because a Good type spell can't be cast by Evil Clerics).

It's possible to take steps to conceal it, but in my experience not many people do that.

So I don't think the real risk here is that you're going to make alignment too easy to determine.

Overemphasizing Alignment

To me, the biggest concern is that by having the world reflect alignment so readily, you're making it more important. Being Good is so important in your world that all magic is affected by it, even when the spell is thematically neutral and doesn't do anything that relates to alignment.

You've elevated alignment to be a more prominent thing. Considering how rigid the alignment system can be and the problems it can cause with player behavior, that's not something I would want to do.

Consider what that means? Normally if I see someone cast a Fireball to take out some creatures, I'd just determine what to think about that based on what I saw, and if I cared about those creatures or not. But now I'm seeing an Evil Fireball. If I'm a Good character, do I have to do something about the evil spellcaster? What if they're on my side? What if the people they're attacking are also evil, but those people are using weapons so I can't tell?

The alignment is so in my face that it distracts from trying to figure out the motivations of the people involved, because literally the first thing you've told me is "that Wizard is evil."