Episode IV
Team -1 is as you say a scan of a theatrical 35mm print, and Harmy’s despecialized edition uses the 2011 Blu-ray as the base, and “undos” all changes using 35mm scans, custom matte paintings, GOUT upscales, custom transitions etc.
In other words, Team Negative 1 release is the REAL theatrical version, the Despecialized edition looks better but some of the parts (e.g. the transitions) are re-created and not authentic.
There have been 5 different audio mixes done for the pre-1997 versions, the 1977 stereo mix, the 1977 4.2 mix (the same “audio content”, just mixed in more channels), and the 1978(?) mono mix (brand new mix using alternate takes, new sound effects etc.). Then there was the 1985 home video remix and the 1993 remix. A nice description of the mixes is here : http://originaltrilogy.com/topic/Star-Wars-sound-mixes/id/15294

Episode V
As far as I know the 70mm version was not preserved. There were also 3 different mixes made, a 6 channel mix, a stereo mix and a mono mix.

Episode VI
I think the best version is either the Despecialized edition or the Team Negative 1 “grindhouse” release.

Episode I
Adywan’s DVD wasn’t the theatrical version, he missed at least one change (the missing CGI bridge). If you want the theatrical version you have to get either one of the TV braodcasts or one of the laserdisc transfers.

Episode II
As far as I know only CAM bootlegs are available. And they all look like crap.

Episode III
There were more changes. https://www.youtube.com/watch?v=IiCn0O4aF_8