Hey, Charles. Glad you like the change. For #1, there's a setting on the Webmail card in Account Settings: Use To: address for replies. If this is toggled on, and the alias allows replies to be sent from it, then when a user replies to a message, it will default to the alias address.
Regarding #2, we're still working on the documentation for the API. We'll be releasing more and more with the next few minor releases, so stay tuned.
Derek Curtis
COO
SmarterTools Inc.
www.smartertools.com