On to the Seelie Court and related deities. In general, I think most of these deities would have priests, and in many cases, they’d probably be druids. While Pixies and Satyrs can’t be priests according to The Complete Book of Humanoids, and Leprechauns can’t according to Polyhedron #116, Demihuman Deities specifically allows sprites, pixies, and leprechauns to be priests of Erevan Ilesere. I see little reason for these races to be able to become priests of an Elven deity, but not priests of their own.
Titania & Oberon – As I outlined earlier, I think it makes sense that faeries can be priests of these gods. Titania might have druids in addition to another type of specialty priest, but I think Oberon would just have specialty priests.
Caoimhin – Killmoulis probably never become priests, so I’m not sure if a priesthood should be created for Caoimhin. I’ll need to read their Monstrous Compendium page again, though.
Damh – Korreds especially and Satyrs to a lesser extent would fit well as druids; however, Damh doesn’t seem very druidic in nature. I’m not sure whether his priests would be druids or something else. Perhaps Satyrs and Korreds who wish to become druids would choose Titania.
Eachthighern – Dolphins can become priests, so why not unicorns and pegasi? In addition, some Pegataurs may worship Eachthighern. I don’t think his priests would be druids, though.
Emmantiensien – Is there a more perfect druidic god in the Seelie Court? He might have some Treant rangers, too, which could make for some really interesting characters.
Fionnghuala – I would probably model her upon Mielikki in the Forgotten Realms, where she doesn’t have actual priests, but instead they’re a sect of another nature deity. Mielikki may actually take her place within the Realms, since they’re pretty similar in character. I dunno that I’d actually merge them, though. Also, since swanmays can only be druids and rangers, it’s a perfect combo.
Nathair Sgiathach – As the god of Faerie Dragons and Pseudodragons, I’d model any priesthood after the other dragon gods. I’d kind of like to see faerie dragons adapted for the Council of Wyrms setting, too.
Squelaiche – As leprechauns can become priests of Erevan Ilesere, I think they should be able to become priests of their own patron. They might even be able to become priest/illusionists.
Verenestra – Another deity who would very likely have druidic priests. They’re probably be modified more than most others, to reflect Verenestra’s focus on charms and beauty, though.
Queen of Air and Darkness – One of my favorite non-human gods, and one with a LOT of potential, especially as one of the few non-drow evil gods with Elven followers. She’d probably also have a priesthood amongst the Quicklings (another favorite of mine). They may be able to multiclass as wizards or illusionists, too.