Salam,
Let me respond to the second issue you raised. You asked if the given verse was an injunction to pray (presumably a lot) during the night. Of course praying during the night is good, but if you read the verse carefully, it's only addressed to the Prophet, and it's actually telling him to
stop praying so much, because he's praying so much it's getting unreasonable! See this:
"Your Lord knows that you stand up praying for nearly two-thirds of the night, or one-half of it and sometimes one third of it, as do other among your followers. God determines the measure of night and day. He knows that you will not be able to do it, so
He has turned to you in mercy. Recite, then, as much of the Quran as is
easy for you."
This verse is advocating moderation. It tells the Prophet that prayer and devotion to God is good and all, but only when taken to reasonable terms.
Secondly, about jinn: I don't know whether they talk to fortune-tellers or not. I doubt they do. There are many fortune-tellers who actually give quite accurate information, but they might actually have the gift or foresight; I doubt they are informed about future events by jinn.
Yes, it's quite possible that jinn eavesdrop in the heavens, considering that they're primarily metaphysical beings, but this is an "ambiguous" or "allegorical" verse and it's not meant to be pursued.
Mia