Just remember that some English pop songs try to sound "cool" by speaking English in a strange way. It's just a way for those kids to get attention. Really, none of your examples are "correct" in standard English, but that's fashion for you. It's so funny that I'm siding with "wanna/gonna" as correct, isn't it? :D

An interesting question. The way to look at is this. gonna, is a shortened form of (to be) going to. It is really only used in informal language. so expanding I ain't gonna. It becomes I am not going to, which is the "correct" form. Similarly with wanna wanna = want to. To make this negative we use do not So I don't wanna = I do not want to. Try changing them to positive from negative. I am gonna - I am going to (continuous tense) I do wanna - I do want to (emphatic and present)

The correct way of saying that is "I'm not gonna" or I'm gonna" and instead of saying "I don't gonna" it would be "I don't wanna" I'm glad you understand gonna/wanna is a lazy way of saying going to/want to, most people are guilty of it here where I live, even me in speech, but when writing nobody ever writes like that.