no, although he did stay with them for a short while....
No, Sol is not a ShadowClan warrior. He is a rogue tom who appears in the "Warriors" book series.
He is a definite shadowclan warrior.
shadowclan
Cinderheart was the Deputy of ShadowClan, so yes. Yet; he passed away from sickness along with most of ShadowClan.
Rowanclaw is a character from the Warriors book series by Erin Hunter. He is a ShadowClan warrior and eventually becomes the deputy of ShadowClan. Rowanclaw is known for his loyalty and strong sense of duty to his Clan.
Sol is the cat that told all the medicine cats that the sun will go out and that they cannot trust Starclan anymore. Shadowclan worships him at first.
I can't find anything about a Willowfur.
ThunderClan, ShadowClan, WindClan, RiverClan, StarClan, SkyClan, DarkClan(not officially).
He was killed by a ShadowClan warrior when ShadowClan driven out WindClan from their home in Secrets of the Clans. Go to Secrets of the Clans: "Raid on the camp!" pages: 31 to 33
Thunderclan, Shadowclan, Windclan, Riverclan, Skyclan, Starclan
Firepaw Fireheart or Firestar
Blossomfall. But there also was a Blossomkit from ShadowClan that was apprenticed too young and fought and died.
Yes, Spottedleaf was killed by a ShadowClan warrior named Clawface in that book.