Australia, New Zealand, Canada, Denmark, France, Germany, Hong Kong, Ireland, Norway, Poland, Portugal, Slovakia, South Korea, Taiwan, United Kingdom, Hungary, Spain, Argentina and soon, Chile.
Those persons who have any of the above-mentioned nationalities and who are 30 years old or younger at the time of applying for the visa.
Yes, at the airport itself, before passing the immigration controls you will have to fill in a paper called “boarding pass for re-entry”.
This card consists of two parts, one will be delivered in immigration when leaving the country, the other will be stapled to your passport and taken on your return.
In theory this is not allowed, although the immigration authorities have the power to make this possible.