What kinds/breeds/varieties of domestic (livestock/pets) and game animals and birds would do well on a 65-square-mile tropical island?

[greybeard]

and often, be able to drink salt water.

Most atolls are volcanic caused but not made of lava. They are coral that rings an underwater or near surface volcano, either extinct, dormant or active.
The volcanic part (the interior) usually subsides over years or centuries and just the coral ring atoll is left.

I've been to Johnston Atoll in the central Pacific. Close to it anyway. It was contaminated with some kind of nuclear weapons radiation.

 

[TwoByrdsMG]

I'll let you know about the Murray Grey beef cattle in 12-18 months. Just prepped a shipment of embryos for Maui.

Wild pigs, goats, donkeys sure seem to do good over there so I imagine that it would be the same if the island is large enough and the feed supply is diverse. If you hit the $1B jackpot and decide you want to really experiment I can help you with a path forward