Wow! I will not attempt to answer all that!
If band width and HD space were a big factor and I wanted
to have a nice Star Wars binge I would watch Harmys:
SW 2.7
ESB 2.0
ROTJ 2.5
I have the ACVHD & .MKV versions of all those plus the earlier releases.
Those have the best image quality and sound. (my opinion)
Then I would be curious about TN1s Star Wars which is very nice, dirt & all!
You might want to read the 1st page of each thread about those projects, that
would explain all the differences in audio tracks, subtitles ect.
As far as those “Other” films, I would just watch my retail versions as I
don’t know of, or care about, any changes made to them.
One point of interest though, any fan preservation here that was synced to
the “GOUT” discs will be able to use the same audio tracks. In other words
the DTS sound track from Harmys 2.7 would “mux” into the TN1 Star Wars.

oops… I think the cows have come home!