Dynamic Forms in Android

I'm learning how to programm Android applications and I'm working on a assignment which is basically create an app that can display dynamic forms that are filled by the user and sent to a server.

But this system has some requirements that I'm not sure exactly the best way to solve it:

1) The application should provide different types of forms, therefore the user can choose the type of form and the activity will be shown respectively the form chosen.

2) The user can add new forms anytime he/she wants.

3) The form's data should be sent to a server.

Based on these requirements, I've been thinking about the solution. What I thought is that I can save the form structure as a file, which can be updated in the app by the server every time the user add a new form type.

Anyway, do you guys have ever worked in an application similar to this? How could I save a form structure as an archive to be called every time choose a specific form? What format should these forms be?

Another questions is what would be the proper way of sending the data to a server? What structure should the data be sent to the server? Should I use JSON?

And finally, what should be the proper way to make the server update the forms in the Android application?

I appreciate any help you can give.

Thank you very much.