From the admin area of WordPress, click on users, then click on the administrator whose information you want to change. You will be able to update that from inside there.
Yes, but only if you are logged in using the same profile that that you wish to change the information for. For example, if you are logged in as user1 and you click on edit my profile it will take you to edit the profile for user1. If you wanted to edit the information for user2 you must do it the other way.
Get yourself around WordPress. Find out every tool available for you. Navigate your dashboard, you'd be surprised how much more you can do with a better knowledge of WordPress.