Your target pages are become hidden. The visitor will be prompted to enter the password to visit the URL. Without the password, they can't get neither target page nor page info or statistics.
You can restrict the access to pages not protected any other ways. For example, a file from Dropbox, Google Drive or any public file hosting.
The copi.st will track information about the number of times users try to visit target URL, separate success and fails.
You can password-protect your bookmarks to prevent unauthorised access to your links. Nobody will ever know what hides behind your browser favorites!
Yes, use 'manage' URL modifier to change any short URL options, change or clear password.