Transit visas do not exist in Chile. There are Tourist Visas in case you need to go through customs to recover your luggage or if you will leave the airport.
Transiting without a visa is permissible for travelers continuing their trip within 24 hours to a third country provided that they have return or onward tickets and that they do not leave the airport.
Any citizen in transit, that stays at the international lounge of the airport waiting for their next flight and will not go through Customs, does not need to apply for a visa.
Tourist visas are given to those who do need to go through customs, either to leave the airport or to simply pass through Customs and Border Security to collect luggage. All visa applications must be submitted to the Consulate of Chile in Wellington, so please review the information online for Tourist Visa application.
This information applies to all citizenships, over and under 18 years old passengers. If under 18-years-old passengers pass through customs, they must depart with both parents/legal guardians and if the minor travels unaccompanied or with only one parent, a travel authorization must be provided, in order to be allowed departure.
There is no hotel accommodation at the airport, but there are lounges:
Santiago de Chile Airport Lounges
Santiago de Chile Airport Guide