You can check requirements for each state by clicking the link under each destination at https://orlandoairports.net/flights/us-service/
No, only international. Check CDC and with the airlines you are traveling with.
Not to fly out of MCO but you do have to meet the requirements that CA has in place. In the end the airline will require you to acknowledge you do not have symptoms and for you to wear a mask. Other than that it is up to you to know and meet any other requirements the destination has.
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