Android / iDevice Application for Private Teacher-Parent Communication

I own a private language school and I'm investigating the feasibility of an application for both Android and iPhone/iPads that would allow for quick and private communication between teachers and parents. The application must allow the teacher to quickly and easily select a student and write a brief note that could include a picture or video of what occurred in class *from a computer in a classroom.* I want to make a special note of this. Again, the teachers must be able to write these notes from computers and not be limited to their mobile devices. Once the teacher submits the note, the corresponding parent would then receive a push notification from their mobile application informing them that a new message had arrived. Parents would have the option of saving or deleting these notifications. Parents would *not* be allowed to send messages back to the teacher. A final feature would include the option to have teachers create groups of parents (or classes) and send bulk messages to the entire class's parents. As some parents have iOS devices and other have Android devices, it's imperative that this would seamlessly work for both. If this is a possible, just a basic template with blank skins that I can edit to my own liking is required. I can do my own graphic work. Many thanks for your time and consideration!