Rendered a clip, with the above set as properties, to HD 1080 24p YUV, but it wouldn't play, and the file was huge. maybe someone could clarify this for me.

I would expect it would be huge, it's a 4:2:2 uncompressed file set up for output to HDCAM over an HDSDI connection. Great for archive, not so hot for editing unless you've got a serious RAID with serious throughput.