If you want to set an expiration date and password when sharing Excel files online, here is how you can do that. It is possible to do both of them when using Excel Online.

Learn how to view or display Document Properties in Excel. Also learn how to remove Excel Properties. Properties or Metadata box displays information about a file.

While you won't be able to edit Excel files with the iPad's Quick Look file viewer, you will be able to view them and even copy and paste data from them.