You can sync your music to each of your devices using the iMac which is referencing the library on your itunes. So all good there. If you want to share the information amongst all your devices then home Sharing will do it. But only if you are in your own network.
If you want to use the same klibrary on your Macbook as your iMac you can point it at the Library on the time capsule.
If you want the content on your Macbook then Home Sharing between computers will let you copy it but it will not copy over playlists etc
Using home sharing you have to have itunes open on your iMac so that the other devices can see it. Also ensure that sleep is not set for your computer.
if using the option of using the time machine music folder as the source music on both the itunes on the Imac and the Itunes on the macbook would the playlists increase play counts from both devices?
i have no seperate content on the macbook and they are both on the same network when im at home and they both sign in as the same itunes account