Ratifying iTunes library changes made from another computer

I recently subscribed to iTunes match. I uploaded my library from my iMac to the cloud. Following that, I authorized my macbook to also use that library and everything worked fine. I have since, however, made some extensive changes to the library on the macbook (song names, album artwork etc, deleted some songs from the cloud etc.). What I want now, is those changes to be reflected to the computer where I initially did the match. I understand that iTunes will not delete the "original" songs from the iMac even if they have been deleted from the cloud. What I want to know is the following:

• If I de-authorize the iMac (the original "match" pc), delete all the local content, then re-download everything from the cloud will the songs come back in the form they were when I first uploaded them? i.e. mp3. On the macbook I see they have an "m4a" extension even though I uploaded .mp3's from the iMac.
• If I re-downloade everything from the cloud will the content have any sort of DRM protection etc? i.e. will I be able to play them on other devices?