Diggle is original to the show, and yes, he's based off of Andy Diggle who has written Green Arrow: Year One.
Cisco is an actual comic book character who had his Vibe identity. He's his own character unrelated to the Flash, but Andrew Kreisberg added him to the Flash lore in the show due to the fact that he relaunched the character in the New 52 cause Andrew worked on comics before he was kicked off the show.
Caitlin has been established as of 2011's New 52 version of Firestorm's comics, but Killer Frost had been around for decades as Firestorm's nemesis as other names. (Such as Louise Lincoln) I believe even longer than Vibe.