Questions about example sentences with, and the definition and usage of "Okinawa"

A: in first case the listener must have already stated that he/she/it has never been to Okinawa and the speaker is surprised or may be didn't hear well first time and just reconfirming. In second case the speaker is asking the listener for first time. Also, "have" is correct instead of "had".

A: They are both correct and natural, and they mean the same thing. There is no difference.

A: generally they can mean the same thing..however

the first sentance could be used more generally..so it can mean on average in the year okinawa is warmer

the second sentance can be used more specifically..so it can mean right now okinawa is much warmer

A: The meaning is the same, but the second example is more metaphorical and would show better skill at English.

A: I want to visit Okinawa, in Japan.
or:
I want to visit the city of Okinawa in Japan.

A: Okinawa is the Southernmost part of Japan.

A: Sentence 2 is perfectly natural.

Regarding sentence 1, it's a bit strange. I would expect "She leaves for Okinawa" to be followed by something like "in a few days", not "right now".

A: 1. They leave is future tense. They leave tomorrow, future.
2. They are leaving for the airport right now. Good sentence.
3. The leave - again future tense. Try, they left for the airport just now.
4. They are leaving for the airport, now/ at this moment/ as we speak. Just now sounds past tense. Just then, just a few moments ago.

Leave - future, left - past, are leaving - present.
Right now - present, just then, just a few moments ago - past tense.

A: It should be "I watched an Okinawa rail(bird) at the shelter in Kunigami village." <--- "an", not "a*.

A: or I live in a small island near Okinawa.

A: Other than "didn't get" as other commenters have mentioned, you could also use "haven't gotten". Also, I think it would be best to replace your "and" with an "or" or a "nor". "Nor" would be the more correct of the two, but "or" is more often used