Question about Templates with SharePoint 2010

Hello,

I have some questions about templates with SharePoint 2010.

Where are templates located on the server?

If I was going to take one template and move it to a different server, how can I do this?

How can I tell what template a site is using?

Can they be customized? How do I customize them? With SharePoint Designer?

Any resources out there about the basics of SharePoint templates?

Thanks.

Paul