"What is the window size of direct canvas?"
What ever you make it?
"I have a game with a 800x60 layout and exported it to direct canvas. The visible part in the iphone seems to be bigger than 800x600 because I sprites outside the layout boundaries in the iphone screen."
As stated here, your problem may be the fact your not taking pixel density into account. You have to worry about more then just the resolution.
"What are the screen sizes for iphone and ipads?"
Take a look here. That should help you out, but you can simply Google easy facts like that. Don't forget.
Hope that helps, but I'm haven't developed on mobile much. Good luck.