I would not accept 1 and 3 anywhere. You will hear the second with some regularity.
Are all of these acceptable in general conversation:
That means imma hafta talk to her myself.
That means I'm gonna hafta talk to them myself.
That means imma have to talk to them myself.
In conversation or text only.
But don't they all mean the same thing?
1 and 3 remind me of the ludicrous fake dialect/accent used by Jar Jar Binks in Star Wars, Episode I. Don't use it.
Remember - if you don't use correct capitalisation, punctuation and spacing, anything you write will be incorrect.