Adam: Here are the tracks that I know of:
Friends Will Be Friends
Album Version A Kind Of Magic: EMI CDP 7 46267 2
Friends Will Be Friends Will Be Friends (Bonus) A Kind Of Magic: EMI CDP 7 46267 2
7" Edit Remix EMI Queen 8
12" Extended EMI 12 Queen 8
Karaoke Instrumental Japan Toshiba EMI TOLW - 3249.50
Promotional Video Greatest Flix I & II: Pioneer PLMPD 01171
The differences between each have been pretty much summed up by your own list:
Extended Version 6:19
Album Version 4:07
7" Edit Remix (Is a hybrid of both)
If I recall correctly, I think the video version and 7" version are almost the same. (As suggested above - it may even be an edit of the video version) - and ofcourse, I refer to the original UK release.
Now to clarify this, when I originally circulated this list the Video Version (4:23) was NOT really available as an audio track to most people - as most still owned mono VHS recorders and DVD's had not been invented.
Infact, quite a few bootleggers made a lot of money selling CDs from video tracks like "Friends Will Be Friends" and "A Kind Of Magic - Highlander closing credits".
Also, I wanted to point out that all the audio formats (Album/12" & 7") were different from each other.
Perhaps it is a little confusing but comparing like for like, even the Queen catalogue lists "Friends Will Be Friends" as album/12" and 7" versions.
As a completist - I want It All - Don't you?
"Listen to them. Children of the night. What music they make."