Of course. Australian Galahs speak like Australian people. The birds aren't actually learning words, they're mimicking sounds. An accent is the sound of a pronunciation. If a parrot is only mimicking sounds with no understanding, it would of course, mimic the accent.
Only to an outsider. Fun fact! Crows have developed a language, it is so ordered that there are actual dialects depending on the crow's location. ie a crow from California sounds different than one from Newfoundland. http://www.cracked.com/article_19042_6-terrifying-ways-crows-are-way-smarter-than-you-think.html
If they are learning the language of the land, I guess they say the words with the natural accent being spoken by the people teaching them.
Not to their original owner
Things that make you say Hmmmm??? lol
why don't you ask one?