If you have activated the option to store passwords in Mozilla Firefox, than you can easily look at all password you have entered when you were browsing websites.
If you need, besides major accounts, an extra account with limited access to data, you can add Windows 8 Guest account. The process is almost the same as in Windows 7.
If you don't want others to use your photos and images without your permission, you can create a so called custom watermark with your name or any other text you want.
If you use a lot of different usernames and passwords it is difficult to remember all of them. KeePass is an interesting solution where all your passwords are kept in one safe place and protected with one password.