MySQL users question

[Michael Ho]

I am trying to create a new user for my new MySql database (press_db) under my CentOS server (Server have CentOS and MySQL installed on it only)

So from the command line I wrote:

> CREATE USER 'dbuser1'@'localhost' IDENTIFIED BY 'password_here';
> GRANT SELECT, INSERT, UPDATE, DELETE, CREATE, DROP ON press_db.* TO 'dbuser1'@'localhost';

and to make sure the user was created I executed the command:
> select user from mysql.user;

but I found that there was 2 'empty' records and also 3 records where the user field = 'root'....so I was wondering, does this mean that my server was hacked where someone added more 'root' users to the table? and if yes how I can distinguish between my original 'root' user and the hackers 'root' user in order to remove their?

Last question, is there a MySQL command where I can test logging to my database using the new user name / password in order to make sure I the new user name / password are working?

Thanks in advance for your time