I bought an X-Large crate for my pup. He has used it since he was 8 weeks old. I never divided it or used a smaller crate. He only had one accident, and that was when he was in the crate for his first time ever.
I don't suggest putting a dog bed in the crate with the pup, he/she will most likely just tear it up. Just some toys.
One thing that I noticed, which kind of drove me crazy, was the sound that was produced when my pup was moving about in his crate. So we solved that problem by putting a piece of cardboard between the wire crate and tray.