OK! You want the Manual of the Planes to start with. It's got an entire section on the Feywild, which parenthetically was written by John Rogers, mastermind behind the TV show Leverage, which has an RPG based on it. (But don't buy the Leverage RPG, it won't help you with fey pact warlocks.)
The aforementioned "Performing the Pact" continues to be useful for the same reasons it was useful for star pact warlocks -- good roleplay advice, and some nice mechanical benefits.
Unfortunately, there's no fey pact equivalent of the really good star pact warlock article. There is, however, a great Feywild article: "Court of Stars: Prince of Frost." It's mostly background material about the Prince of Frost, a powerful evil fey being. There are also several pages in the back directly addressing warlock pacts with the Prince, including both roleplaying material and mechanical crunch.
Similarly, Dungeon had a Creature Incarnations article on Fomorians. It's not oriented towards warlocks, but if you're looking for great stuff on the Feywild, it's worth reading.
If you're looking for adventures, King of the Trollhaunt Warrens takes place in and around the Feywild. I don't find it hugely evocative of the fey spirit except maybe in the last section, but it does offer one perspective. Similarly, the RPGA module The Lady in Flames is strongly Feywild flavored.
Continuing to third party resources, Goodman Games comes to our aid again, with Creature Cache 4: Fey Folk. It's purely a monster book, so if you want more Feywild denizens, it's where to go. Kobold Quarterly has a fey-themed adventure, Courts of the Shadow Fey, which might also be useful.