Am I a man or am I a muppet? If I'm a muppet then I'm a very manly muppet!
The rules are somewhat ambiguous on what exactly a "round" is. I gather that a round just consists of as many turns as it takes until all players have taken a truck.
You're correct - a round is a series of player turns which ends when all player have claimed a truck & placed their new animals.
Sub-question: in a 2-player game, once one player has ended their round, does the other player just keep taking their turns back to back until they take a truck?
Also correct - when 1 player takes their truck, the other player may take back-to-back turns until they also take a truck.