Hi. Welcome to the forum. I'm glad you enjoy the Despecialized Editions.

First - before you post in a thread, nobody expects you to read 250 pages or so but you should always read the first post - people usually edit it to add new important info.

The first post of this thread for example says this (it's the first line of text after the title too):

If you find any mistakes, please PM me. Posting in the thread may ruin the experience for someone else!!!

It also says this:

...the film received an extensive shot by shot colour correction based on a fade free 1977 I.B. Technicolor Print.

The Blu-Ray will be 720p for various reasons ranging from my not being able to work with 1080p on my hardware to the other sources being too low a quality to be put together with 1080p footage.
But because the official BD is sourced from an eight years old 1080p transfer, which has been cleaned up with automated software, the level of detail isn't much different anyway. Here's a comparison of raw BD screenshot and the same screenshot resized to 720p and then scaled back up:

And lastly, no, the Biggs scene was conclusively never present in any officially released cut prior to 1997.