Currently our API only has the ability to create a custom-coded campaign using HTML or XHTML. You can find more information on this topic in the Creating a Campaign How-To Guide of our REST API Reference page.
Regarding your question about scheduling and sending emails, we do not currently support that feature using the API. At this time the only way to send emails is through our website. Unfortunately, I cannot provide you with a time frame of when we this feature would be released. You can find more information on this and other enhancement requests on our API Enhancement Requests forum.