Lyrically, I think "Heartbeat Song" is the weakest by far. "Piece By Piece" will have to grow on me a bit more; I like it more and more with every listen. But I think it'll be one of the best songs on the album. I'm so ready for her album! I didn't realize that it's only a week away!
And as for the Leona Lewis single, Ichi, I think they said her album will be out in July, so I'm guessing it's still a few months away, but I don't know. She previewed it a while ago and I can't imagine her waiting that long to release it. It's hard to say, but she's been hinting that she's working on new music for a while, so I'm guessing it's coming soon!