Hm...I don't really know...anything about Pocaloid but I've seen things here and there so I can try to help.
1. Pocaloid editors are a thing, I think? The only one I know for certain about is that Piapro Studio has no been cracked yet, at least I remember seeing thatbbaxk on VocaloidOtaku.
2. As far as I know, they don't. Have serials. I think they're reprogrammed to take out the need for serials or something.
3. I believe sometimes it says Pocaloid instead of Vocaloid, and at least from v2, they change the colors? Don't know if that applies to V4 too.
You can read the
wiki article on Pocaloid to learn more about what to look for. That's whrre a lot of my knowledge is from.