Damn I didn't know it became free either. For some reason when I placed Reach on my Xbox One (disc and digital) xbox live said I didn't have all the DLC, which I have had since its original release. Needless to say I was pretty annoyed but I love Halo and I liked Halo Reach so I parted with a few bucks to purchase the DLC again on Xbox One so I can play my game and content... looks like I get burned again but its for the best that its free for everyone.
But anyway, I am totally down to help out with the DLC achievements. I think the last 3 I have are all CFT related.