I'm still working on these points. I have a feeling that I might still keep the 'reveal' of Palpatine for ROTJ. Until then, he would be a character spoken of but not shown, as in ANH. I'm working on capturing the 'moment in time' feel of ANH, i.e. telling a whole story in each episode but revealing information about the characters and the universe around them as we go. Obviously Vader talks to Palpatine via hologram in ESB but the true character is not really seen until ROTJ. I think there will be talk among the Jedi about the Sith and Palpatine's involvement with them but I'll keep any actual revelations of Palpatine's true power until ROTJ.

I'd also like to avoid the sort of explanatory dialogue that started to appear in the PT. I was discussing this on ORS recently. I feel that the appearance of pseudo-scientific explanations for things, e.g. midichlorians, are a departure from the approach in the OT, which took you right into the SW universe and you could draw whatever conclusions you thought best from what you saw.