All single tongue for me.....but I have practiced it double-tongued just in case.....
The end - definitely double tongued.
Everyone talks about the moving notes in the opening, but also remember, coming off of the tied "G" on time (don't have music in front of me, I think it is the third or fourth full measure), and not late, has a lot to do with how the rest of the excerpt will go. Many folks sit on that note too long or don't make an accurate break from it when continuing on and then spend a few measures playing "catch-up". Answer: make sure to subdivide in your mind on the tied note.
I have to add, the second movement of the Ravel is one of the most beautiful and tender in all of piano concerto rep....simply beautiful. However, the
most tender and heartwarming for me is the second movement of Beethoven's "The Emperor". Tears EVERY time.