You can change your email here: https://accounts.agenda.com/credentials/changeemail
More information about Agenda Accounts is available here: Accounts in Agenda
We will see what we can do for other sync options. The problem is really that everyone wants a different one.
Publishing is probably beyond the scope of our app. You can export notes in HTML or markdown, which makes it easier to paste into WordPress or whatever you are using.
For a full fledged blogging app, take a look at something like MarsEdit.
Thanks for the feedback!