Amongst the SPAM in my inbox today I came accross a link to a news story over at Empire magazine.
They have some information from a small interview with Lucas.
First part is nothing unexpected, but the second part is interesting.

"If, after the initial 'wow!' factor had faded, you were left with a number of niggling questions after watching Attack of The Clones, you certainly wouldn't be the only ones. (Ahoy there! Spoilers be dead ahead!) How come Yoda uses a cane if he doesn't need it? Why is Dooku so surprised to see the clone army when he helped commission it? But most of all, why in God's name don't R2-D2 and C-3PO recognise anyone in Episodes IV, V and VI since they've met Obi-Wan repeatedly, visited the Lars homestead before and Threepio was built by Darth Vader for Chrissakes!"

Well, knowing how fraught the geeky among us can get over these things, good old George decided to clear that last one up to spare fans from unnecessary sleepless nights. "His memory system has been erased and so has R2's, so they don't remember anything from the first trilogy," he told E! News Daily. "I'm telling you something from Episode III, I shouldn't be telling you that but I think most of the fans already know that."

Another nugget of news carefully extracted from the halls of Lucasfilm was that Natalie Portman will be contributing to additional scenes for the original trilogy. Apparently, while shooting Episode III, Lucas will be leading Portman off to shoot some footage for Return of The Jedi, which will make its appearance on the eventual DVD release. The fact that Padme is supposed to have died long before the events in Episode IV is surely not lost on Lucas so the possibility of misty-eyed flashbacks can't be ruled out.

http://www.empireonline.co.uk/news/news.asp?3938

About Dooku being surprised. He was in the presense of some of the break away nations from the republic. He has to sell the fact that he was surprised so he can still get support from these nations. If the nations found out that he had set them up, they would probably rejoin the republic and there would be no clone war and no need to continue using the cloned storm troopers. Darth Sidious needs the war to continue so he can gain more power and continue using the storm troopers. This is all just my opinion though. Anyways, I am confident that Lucas will answer all the questions in the final episode, III.