Why have 3 songs from a recent download from iTunes got a ''! next to them and won't sync to playlist?
You are seeing the exclamation point because iTunes doesn't know where to find the song. 

Using iCloud, you can download those three songs again without having to pay. You can do this by going to the iTunes store, navigate to Quick Links on the right, and click the Purchased link. Search for your songs and you can redownload them.