By the way, I worked out that a good page size for the A3 in Word is 210mm in width (a4 width) and 138mm in depth. This will enable you to work with pages that are pretty much the screen size of the a3 when zoomed to full width. When you process files when converting, I find that Good Quality is better than 'Best Quality' because the file size is 5 times less and page turning response is faster when using the A3.
If you are proficient with Word (ie. can do moveable text boxes, colorize text, or insert floating backgrounds behind the text), then you could create your own presentation style material quite easily.