What do you manage?

We manage security for all servers including PHP, .NET, and the operating systems What do I manage? You are responsible for securing your website code. 

What security do you specifically provide?

Firewalls at the infrastructure level, DDoS mitigation, antispam and antivirus (for legacy email accounts only).

What ports are open for me to use?

All standard ports such as...80(HTTP), 443(HTTPS), 587(SMTP), 465(SMTPS), etc.

Database Security

On Cloud Sites we fully manage the back-end infrastructure and are responsible for server-side security, patching, etc.  Your database will be secure assuming you create a unique database username and secure strong password and keep this safe.  Your database will be provisioned on a database cluster separate from the web servers running your site/application for greater performance and redundancy.

Password Protection

Can we lock down sub domains with username and password without having to use script or code?

No, if you want password protection you have to set that up in your code (for folders or groups of folders)