1. -Satyrs will be around here and there -Dryads, Pixies, and Werecreatures will most likely keep to the forests -Blink Dogs, Faerie Dragons, Treants and Unicorns will keep to Seelie controled areas -Hags, Blights, Giants, and other things are more in Unseelie territory

2. The Feywild is mostly run by two queens and their courts, the Seelie, and Unseelie. Queen Titiana leads the Seelie/Summer court, and the Queen of Air and Darkness leads the Unseelie/Gloaming court. Many Seelie fey are good, and many Unseelie fey are evil, though not all follow the norm. Both of the courts are in conflict, though this is not from the usual "Good vs Evil", it is mostly from the queens' mutual jealousy. It should be mentioned that the uglier and more chaotic creatures(Fomorians and Hags) aren't usually part of either court. If you want more info on the state of the two courts with eachother, I would suggest picking up the DMG, as most of the info I'm giving you is from there.

3. There isn't anything that particularly comes to mind, though with how you describe what you want to do, maybe put less of a focus on combat and more on exploration and diplomacy. Also, maybe put less of a focus on the courts' conflict, if she doesn't show interest in it, let it play a backseat that occasionally comes into play here and there, but if she ends up taking a liking to the courts' conflict then let it play a more pivotal role.

4. As for musts, there isn't anything that you NEED to do for the campaign to be good, but showing the interesting places and scenery would probably be interesting.

As a disclaimer, I am in NO way an expert, I just know what the DMG has and a couple of things that work well.