I, for one, would prefer to leave the AT-ATs with that stop-motion action as it does give the impression that these machines are big and heavy with a real lumbering motion. A few more Snowspeeders would be good, but then it sounds like there is only really Rogue Squadron, so I'd guess bringing the numbers up to 12 (with most in the background) might be an idea. Maybe a couple more AT-STs perhaps? I'm sure those Rebel laser cannon towers would have been powerful enough to kill a couple of those!
It's a shame there isn't any footage of the extended Luke-Lando rescue at the end of the movie as it would have been good to see that.
I've given my opinion before that there isn't a lot to change about ESB and I stick by that opinion. The Vader sequence on Cloud City is probably the most jarring aspect, given it is blatantly not the original cast doing that bit and it was cobbled together with footage from Jedi, so am glad to see that Adywan will be removing or changing it.
As for the Yoda puppet, I think this is probably more alive and expressive than the CGI (and PT puppet) efforts made in the PT...whilst the CGI model is technologically superior, there's something about an actor actually reacting to something in front of him that makes the whole atmosphere work. Can you imagine Mark Hamill having to act to nothing as Ewan McGregor did in most of the PT? I'd reckon the whole Dagobah sequence would have come off really badly! I'd leave Yoda free of any cosmetic changes...
Now just quickly back to Jedi and Luke's green lightsaber...Remember, Luke lost his original saber and would have made a new one based on his mentor's one - since he had two mentors, perhaps he modelled the actual hilt on Obi-Wan's and took Yoda's green colour. After all, we don't know that Yoda didn't show him some saber skills during his time on Dagobah...
Sorry if this was all addressed...been a bit busy! :p