Hey, Bobson! I think you’re on to something cool here, and a bunch of the clips look fantastic so far, but I think you’re using certain bits in ways that aren’t quite accurate. For example, I think that bit with the probe coming to camera through the flames isn’t supposed to be right after it crashes. I think it’s pretty clearly the scene from the script where the Probot wipes out a Rebel outpost before Han and Chewie are sent out to deal with it. I think that’s why the wreckage is pretty clear in frame. The actual destruction of the base is off-screen in the fifth draft, and the shot of the aftermath that it describes is almost exactly like this shot from the eBook.

Secondly, I think your edit of the Echo Base Wampa attack is a bit wonky on the continuity. Granted, the footage as presented isn’t exactly the most easy stuff to work with, but I think it’s very clear to see the shot from the finished film of the ice crumbling onto R2’s head is what segued into the wall collapsing, and then lead to him getting locked in the corridor. The scene of him peaking from the wall occurs during the troopers fighting the Wampa off in the script, and at this point I would say having the sound of the Wampa being defeated over this shot is probably the best bet with the available footage. It’s hard to say if the scene’s scripted finale, with the Wampa being defeated by some large gattling-gun style blaster, was ever filmed, but my money is on no.

And one last thing, I think a lot of the shots of the actual Wampa suit during the attack scene were probably shot just for safety. The script describes quick snippets all until you see the corpse on the floor at the very end.

Good luck on this! I think you may try perusing the sound effects wiki for the sound design question. In 1979, Burtt would still be using stock effects as well as his own recordings.