It depends on which manga you're referring to. Some are completed, while others are still ongoing. You might need to provide more specific details about the manga for a precise answer.
Well, to know if a manga is finished, you need to check the latest updates from the publisher or the official manga platform. Sometimes it's clearly stated, but for some less popular ones, it might take a bit of digging.
I can't give you any information about the whole allegro script. Kuaiban is a traditional Chinese art form, usually sung by an actor, which includes common sense, historical events, folklore, etc.