Use the number of isolation counters on Quarantine Field as its triggered ability is put on the stack to determine how many targets you may choose. Once the targets are chosen, the number of targets the ability has is locked in. Changing the number of isolation counters on Quarantine Field won’t change how many nonland permanents are exiled.

If Quarantine Field exiles multiple permanents, those cards all return to the battlefield at the same time.

If Quarantine Field leaves the battlefield before its triggered ability resolves, no permanents will be exiled.

Auras attached to the exiled permanents will be put into their owners’ graveyards. Equipment attached to the exiled creatures will become unattached and remain on the battlefield. Any counters on the exiled permanents will cease to exist.

If a token is exiled, it ceases to exist. It won’t be returned to the battlefield.

The exiled cards return to the battlefield immediately after Quarantine Field leaves the battlefield. Nothing happens between the two events, including state-based actions.

In a multiplayer game, if Quarantine Field’s owner leaves the game, the exiled cards will return to the battlefield. Because the one-shot effect that returns the cards isn’t an ability that goes on the stack, it won’t cease to exist along with the leaving player’s spells and abilities on the stack.