How to make a Windows Mobile based WinForms .Net application easily changeable?

I need to build a Win Mobile WinForms .Net application that once developed will be easy to morph or adjust to new user requirements quickly (including changes in GUI). The main objective is to minimize the development time (development to production roll-out effor开发者_StackOverflow社区t). Also, a nice thing to have is to be able to test it in an automated way.

The application must be able to: 1) Persist state (may use a local database); 2) Sync data across (via Radio or WiFi); 3) Exchange info with a desktop PC or a central server;