-You can only audition for roles in the Harry Potter movies, if you live in the United Kingdom, or Europe I believe.
Auditions are closed now for all Harry Potter films. There are also regulations about who can audition. For example, you must be British or Irish to audition.
Only UK residents can audition for the Harry Potter movies.
You can't. All Harry Potter actors must be British unless the character is from another country.
Go to wherever the auditions are being held.
You can't you must be from Scotland, England Ireland or Wales.
London, the same place as all the auditions are. The audtitions address with be with the auditions announcement. Living in Ireland won't mean a different audition place.
You don't. The movie has already been casted, filmed, and released.
Then chances are you won't make it, unless you live there for a long time and have a strong British accent.
The final Harry Potter movie completed filming in 2010.The spin-off series, Fantastic Beasts and Where to Find Them is currently in production. If there are any open auditions, they will be announced in the media.
There is no such thing as a 'British' accent. The accent commonly heard in Harry Potter is the ENGLISH accent. I can see no reason why anyone would stop you from auditioning for a part.
You have to write to the Harry Potter Casting Office in the UK, and if you really do have the potential, I'm sure you'll be able to do it!