If you saved a password for a website using Safari, it is saved in your keychain (along with passwords to various other things like wireless networks). In /Applications/Utilities/ there is an app called Keychain Access that will allow you to see all of your passwords. Open the Keychain Access app, click on Passwords in the Category List on the left side, and find the website in the main list on the right. Double click on it, then click the Show Password checkbox. Type in your password if it asks, and it will show you the password.
As for downsizing pictures, I'm assuming you want to decrease the resolution. Using iPhoto, you can export photos to one of three default sizes, or use a custom size. You also have the option to automatically decrease photo sizes when you attach them to an email.