Same content will not help you in any way. You can use article spinning software to spin master copy and then can submit its different spinned copies to all directories.
Submit to the best directory first (eg ezine); many directories will use copyscape (or similar) to weed out all duplicate content artilces but some lesser pr directories don't. Some people submit same article to lots of directories and a few will get indexed; others spin article and then submit - they say more then get indexed.
Try to rewrite the article every time you want to submit it in different directory. Try to change a least 40% of the content.
You can submit an article to multiple directories but it makes sense to keep the articles unique. I don't recommend spinning. You can put some efforts into rewriting.
yes, you can but not suggested. better re-write them before you submit them to multi article submission site