BPM is Beats Per Minute - the tempo of the song. Nothing to do with bitrate or ratings.
You're looking for the "Bitrate" field in MB. It's not a tag - you can't set or edit it. It's read from the bitrate of the file. If you right click the top of any list of files where the headings are and then select "Set Displayed Fields..." You'll see it there.
There are also, "Encoder," "Encoding Quality," "Quality," "Sample Rate," and ."ext" fields that give various aspects of the information you're looking for. Again, these are not tags. They report what the file is.