"Anyways" isn't a word, but it's sometimes used as slang to mean "anyway". I've never heard it used in Australia, so it must be a regional thing.
I just looked it up, and "anywise" is an archaic form of "anyways". I thought that "anyways" was a relatively recent thing, but apparently it comes straight from "anywise".
"Ain't" isn't standard English and is very informal. Exactly how informal it is and whether it's correct is somewhat controversial. I'll try to break it down for you.
Most people aren't aware that it was originally an abbreviation of "am not" hundreds of years ago. It's considered a characteristic of African American Vernacular, but people often use it to sound cool. Nowadays it's used in place of almost any abbreviation ("am not", "is not", "are not", "do not", "does not" etc). It's mainly used in the southern US, but apparently there are some dialects in England that still use it. It's generally considered to be a sign of being uneducated and people who do use it are usually associated with rap culture (and many people use it just for that reason). I say "generally" because some people do use it naturally as part of their dialect, but unless you know you're speaking to one of those people I suggest you avoid it altogether, especially as an English learner.
"Holy moly!" is an expression of surprise. It's considered much more polite than other, expletive versions which begin with "holy".