And as far as that last point goes: even Tolkien wasn't above renaming somebody else's character and reusing him. For instance, he got the name "Grima Wormtongue" from the hero of an Icelandic saga who was named "Gunnlaug Worm-tongue" (for his skill at poetry, not his evil cunning).
Éomer was the name of a guy mentioned in Beowulf whose name isn't actually in the surviving manuscript, but was re-inserted through correction of scribal errors.
And King Théoden himself was named after the protagonist of a late 19th century William Morris novel: a Germanic chieftain named Thiodolf, who dies valiantly repelling an assault by a Roman legion.