Selecting a protocol (HTTP/HTTPS)
Looks like you can only choose one and that's almost always going to be HTTP. You can add others later. The others are mostly for non-visual websites; web services and the like.
Pass-thru Authentication
Also known as delegation is the process of using the authenticated user account provided by the web client to IIS to gain access to resources secured with ACLs and SIDs.
Host Header Names
Microsoft Internet Information Services (IIS) allows you to map multiple Web sites with the same port number to a single IP address by using a feature called Host Header Names. By assigning a unique host header name to each Web site, this feature allows you to map more than one Web site to an IP address.