iTunes Match cache vs download

Hi all,

I've had iTunes Match since Februrary and, on the whole, it has been a wonderful service despite some glitches, errors and lack of communication from Apple regarding some of its behaviour.

I have a 64 GB iPhone 5 and the same capacity iPad 3. Now, I have lots of music downloaded onto my devices (via the download button or synced with iTunes Match enabled computer). My question is: what happens if I just play the track as opposed to hitting the download button? The track also appears as downloaded. So, is it? If so, how can I clear out these cached tracks instead of the actually downloaded songs as I cannot seem to delete them.

I ask this because I want to keep lots of my music on the device itself for the many times when I'm in the subway or when Internet is not accessible. Yet, I don't want the cached music filling up the rest of my storage and affecting my ability to add photos, videos, apps, etc.

I wish the service allowed you to actually stream tracks without caching them, and download only to the device if you tell it to. But, alas, this does not appear to be the case.

Thank you!