zimbra passwords

[Tsu]

I have two questions.

1> How do I find the zimbra account that gets created on an installation. Or is it common practice to simply reset that password of that account to something you know after installation. If it is, does this break anything in zimbra or do I have to update any configuration files?

2> Is there any logging of what users do? For example, which admin account created a user account. Which admin account deleted and account. Or check when an admin account's password has been changed?

Thanks in advanced