First of all, the password field in login should be changed to type "password" so it doesn't display it in plain text.
Secondly, if the passwords have been leaked, that's probably because you were storing them on the server in plaintext. in the PHP code, run the sha1() function, then store the hash in the database under "password". Then, when someone logs in, run the function again on the password they're attempting to log in with, and compare the sha1 hashes. that way if anyone gets into the database, all they'll see is the encrypted string of the password, and no more password leaks.
Thirdly, might be worth adding some Ajax into the character page. Gets kinda tiring having to constantly reload the page every time you change an attribute or want to view items in the shop.