Can I use Creative Cloud libraries in InDesign?

When Creative Cloud Libraries was introduced at MAX in October (together with the new CC releases), I believe they said that it would be extended in the future to other applications. InDesign is a likely candidate. Adobe doesn't pre-announce products so you'll have to wait like the rest of us.

At the moment not. But you can use them in Illustrator or Photoshop, create a new document, place the objects there and save it as PDF and place it into InDesign. That's the way I would recommend to do it anyway.