ABC, all are stereo mixes except for the version hairy_hen and satanika did, the 80 esb mix I am working on is stereo and I will not upmix to 5.1, I have done tons of upmixes for edits I have done where the extended or deleted scenes were only 2.0 and the film was 5.1, so I had to upmix to get a perfect match up.

hope this answered your question.

OH, and as far as bitrate, on Star Wars I used 192 on the 3 stereo mixes, 96 on the mono, and hairy_hen 5.1 is 448 to get them all to fit, because the video is at 6500 avg.