Best advice is do not go to head office as you will just have to wait till they have a open day for an interview.
They do not have time and will not interview anyone who just rocks up. Also Dubai interviews are always packed.
My advice to you is to find out how many people tend to attend the open days in your area. Some city's have between 500-2000 people and others will only average around 100. If you want to fly to a interview check the countrys around you and read threads to find out where would be your best chance.
Once employed by Emirates they will take care of your Visa.
Good Luck
