The poster prints out at 11x17 ("tabloid") size. The poster includes the various classes that make up the HttpClient family of classes and how they interrelate and includes 5 small code samples that demonstrate using the classes.
Yes, you get some information about the SSL connection. In particular the HttpRequestMessage has a TranportInformation property that includes the SSL certificate. For validation, I'd recommend creating a simple filter that, on getting a response, checks the responses' httpRequest message for the transport information. If you decide that the SSL isn't good enough, you can then just kill the response entirely. By placing the check in a filter, you can have a good check without having to clutter up the rest of your app logic.
The TransportInformation ServerCertificate is an ordinary Windows.Security.Cryptography.Certificates.Certifcate object. That object includes an Issuer.
You can control the number of connection with the HttpBaseProtocolFilter "MaxConnectionsPerServer" value.