I got the DVDs from where else? Amazon. I got the Terminator and T2 - The Ultimate Edition and T3 Widescreen from there. It broke my heart when they released T2 - Extreme on DVD.
Man, 18 minutes of new footage apart from the 16 minutes of extra footage on the Ultimate Edition, three movie formats, normal, Ultimate and Extended and also in WMA9+5.1 format for the PC, plus an alternate ending.
I sat through the whole trilogy this morning. You can see the T-101 being referenced as T-800 Model 101 when you can see the HUD of the Terminator. And the Terminator in T3 is called a Series 850 "with an upgraded chassis" in the featurettes on Disc 2. I see it this way, CRS and Skynet have the same naming conventions. The Terminator is based on a Sgt. Candy, who works with Gen. Robert Brewster, Kate's father, in the military base. This becomes apparent when you see Gen. Brewster shocked by the appearance of the Terminator at his base and asks him, "Sgt. Candy?" and he answers "Negative."
Apparently, once the T-1s tear the base apart and Skynet takes control, it comes to the conclusion that it would be easier to take out humans if it could make the Terminators resemble the humans. It gets its hands on Sgt. Candy, and models the "human" Terminator with both the endoskeleton and the outer living tissue to Sgt. Candy's likeness. It names the "human" Terminators Series 800, while the other Terminators including the spiders, the tanks, and the Hunter-Killer choppers (which it perfects from the CRS labs. Its earlier models can be seen in T3 as part of the "unmanned military flights" that the T-800 talks about in T2) Obviously, Arnold's Sgt. Candy is Model-101 for both Series 800 and Series 850.
The Series 850 is designed to be more battle-tough and they're the ones that you see as mere endoskeletons in the future wars. With a tougher chassis (heck it withstands a direct plasma cannon attack from the T-X), the Series 850 is also powered by dual hydrogen fuel cells, unlike the Series 800, which runs on a primary hydrogen fuel cell with a reserve alkaline battery. The Series 850 also has advanced tactical routines built into it and enabled to better understand and counter the enemy's moves.
The T-1000 is so advanced that even Skynet hesistates for a few seconds before sending it out. Of course, for a huge AI, a few seconds is an eternity, so you could say Skynet thinks a long time before sending out the T-1000. According to the featurettes, the T-1000 is programmed with a single rule - "to complete the objectives no matter what the cost" and Skynet itself is afraid that it might do something that would endanger itself. In fact, it first sends the first Terminator back and then waits until the very last second when the humans pull the plug to send the T-1000 back. A photo gallery on the DVD shows an older John Connor standing in front of a huge assembly plant with hundreds of Arnolds on racks and a huge storage case with the shape of the T-1000 and a single drop of the alloy he's made of. These haven't made it into the Ultimate Edition, dont know if they are in T2 - Extreme.
And yes, the Ultimate Edition features deleted scenes where Kyle Reese visits Sarah in the asylum, and where Sarah nearly kills the T-800 by smashing its CPU with a hammer when John takes it out to change the read-only status of the chip so that it can be more human. It features a LOT of deleted scenes in the movie. Pity I cant see the "Future Coda" alternate ending.