Elan,
Canappi generates code, this code can easily be customized to do what you need to do. Canappi itself accelerates the development of views, the wiring of these views into a navigation path (menus, buttons, ...). The real key differentiator is the integration of the back-end into Canappi's programming model.
Push notifications in on our road map, but again it can easily be added as custom code.
Canappi supports logins. On the front-end Canappi supports "user defaults" in which you can store username and password. Any user defaults can be passed to an operation to authenticate the call. Canappi also generates back-end services (PHP / MySQL) and HTML forms (with authentication). You can declare an Entity (for instance the entity for users) to be the Login entity. So I would say 2) is well supported (you can check
http://www.wikityo.org which was built with it).
We currently support iOS and Android, we might be able add support for HTML5 by end of the year. We actually do generate HTML today for Symbian (WRT) but we no longer maintain that part of the code generator.
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JJ-