Forum:KB:Evolution of the Palpatine Character and his Portrayal

As im born in 1988, being too young too understand hte background of the Prequel series, and some retcon-like elements, ive got a few questions regarding to Off-Universe developments. (im not a natural english-speaker, please show discretion.)

Palpatine Character: As the Senator/Chancellor Palpatine was presented in TPM, was it known to the general audience, that he will eventually become the Emperor from the Original Trilogy? or was it only known to those with high-grade background knowledge from non-theatrical-release scources? (like novels,guides, official statements...) Was the Emperor referred to as Palpatine in the Original Trilogy or Releases related closely to  the Original Trilogy?

Was there a mention of the "Sith Order" before Prequel Trilogy or release sclosely related to the Prequel Trilogy?

I have not found any Off-universe material that would provide information about the Palpatine-Evolution being a 'surprise' for the audience (like Vaders Fatherhood,). So i would be very grateful for any information on the subject.