Did you notice that t-1000 never talks to t-800, he doesn't say a single word to him,
he talks with almost all the other characters in the film, he even talks to John towards the end.
In Terminator 3 t-x never talks with t-800 either. Do you think it means anything? Or is it "just because"?
Quite simple, the have absolutely no reason whatsoever to say a word to each other.
They are both aware that they are Terminators. They are also aware of each others' mission and purpose. Taunts, threats or any form of verbal "psychological warfare" serves absolutely no purpose since they are machines without emotions.
the terminators, and the machines as a whole, are made in a way to perform as efficiently as possible. calculate every action before its taken and always do whatever is needed.
they have no NEED to communicate with eachother, at least not verbally, so they just wont do it. although it is very possible they did communicate the way computers do, but i doubt it because they dont have any feelings to express.
the 'asta la vista baby' obviously a comedic relief but he also learned it from john when he told him "and if someone comes off to you with an attitude" "and if you want to shine them on it 'asta la vista baby'".
i love the fact that everything is so thought about in this movie. complete perfection.