[Hall of Famer]

The SQL state message says that your DB username is incorrect or that it does not have privilege to access your database. Did you make sure you select all privileges when creating a database? Sometimes users either do not know how to do this, or they just happen to forget the moment they create a database user.

I am not sure for the second problem you have, will investigate it further.

For the getimagesize warning, its not really affecting your site in any way except for the annoying message. To get rid of it, simply change getimagesize to @getimagesize and the warning goes away.