To clarify the "yeah, nah". It often depends on the order, e.g:
"Want to go out tonight?" "Yeah nah let's stay home." ('nah' last = no)
"Should we leave now?" "Nah yeah let's go." ('yeah' last = yes).
Sometimes "yeah nah" by itself said strongly can be synonymous with "no way". Sometimes "nah yeah" said strongly can be synonymous with "hell yeah".
Australian is the best dialect of English.