1. Enigmatic Bishounen: Void Mage (Katanas) - In charge of Hollow Bastion
2. could be Mickey: Holy Mage (Kingdom Key) - Could be in charge of Twilight Town
3. Xaldane: Wind Mage (Naginatas) - In charge of Fabled Countryside
4. Vexen: Ice Mage (Shield) - ???, Dead
5. Lexaeus: Earth Mage (Tomahawk) - ???, Dead
6. Zexion: could be Poison/Status Mage (had a cauldron/scrying crystal thing) - ???, Dead
7. could be Luxord: could be Timespace Mage (???) - In charge of Black Pearl
8. Axel: Fire Mage (Chakrams) - could be Twilight Town
9. Demyx: Water Mage (Sitar) - in charge of Olympus Coliseum
10. could be BHK/Sora (blonde): Attack/Support Mage (Oblivion & Oathkeeper) - could be in charge of Deep Dive
11. Marluxia: Life Mage (Scythe) - in charge of Castle Oblivion, Dead
12. Larxene: Thunder Mage (Kunai) - ???, Dead
13. could be Riku: Dark Mage (Soul Eater) - in charge of Land of Dragons
the ranking also seems to be based on seniority, seeing as Enig is the original member, vexen through zexion are veterans, axel is only somewhat new, and Marluxia, Larxene are pure neophytes
all of these have been seen in the black cloaks, so are almost certainly in "the group in the black cloaks)
Nature magic in FF is Life/Restorative Magic
Also, Zexion said he smelt darkness in the wind, but so did Riku. It's a power from darkness or twilight that Zexion can use somewhat becuase he has trained and is a Poison/Status Mage, and Riku is a Dark Mage, so he can use it naturally
Also, notice that while the Order members use name or rank (you're only number 11, Marluxia!) to call each other, they never call the Superior number 1. So, even if Ansem/DiZ is the Superior, he is probably not #1, especially since he doesn't have the black cloak. He could be completely above the ranking system, though.