Never write more than 3 words.
If the answer is a number, you can write the number. 300 (or you can write three hundred), 1918, etc.
Be careful to read the whole sentence to make sure your answer fits grammatically. For example, if I wrote 'across the ocean' as my answer to the airship question, I wouldn't get a point. It says 'to' earlier in the sentence. See?
The sentences on your paper are different from what you hear on the recording. But the words you write should be exactly the same as what you hear.
Spelling isn't super-important in this part of the exam, though if you spell something really incorrectly you could miss a point.