Re: Angels
Well I’ve read that Iblees was a jinn, though I can’t remember the source exactly. But another characteristic of angels is that they can’t disobey so they can’t “fall”. As far as gender, I told you I don’t know what the technical answer is there, but they’re closer to male than female. All their names are names of men, e.g. Jibra’il, Mika’il etc. And when they would assume the form of humans, they would assume the form of men.
The names ending with eel don’t necessarily imply they’re angels. You have a bunch of names that end with the same syllable who aren’t angels. To name a few, Habeel, Qabeel, Hizqeel, and as you mentioned, Isra’eel. These are all names of people.