how to design software using the patterns for mobile apps

I need to develop an mobile app in Android which will be used by few office people only and below are the requirements :

• Generally in office work-space or meeting rooms we have WAP to access internet,which is connected to Router and then to Internet server.
• Now the app should be able to communicate to WAP, Router to get their status.
• app should be for mobile devices.
• only registered users can use this app
• only single app on each mobile
• 1st install the app and register with respective company before using it.
• as of now app is for Android platform but in future may need same app for iOS mobiles.

I need suggestion/guidance on how design the app using before starting the code. As of now i can think of using 2 design patterns i.e. Singleton and Factory Pattern (for User registration). Also i'm not sure in which language should i develop communication library so that it can be used cross-platform also.

Please throw some light on above.

Thanks,