Apart from the last one (which presumes that the application is being run on a phone - which is not all that Windows Mobile can be used for), how is this different from testing any typical application and OS combination?
Assuming its an application for mobile phone
1> security checks, firewalls etc.
2> internet connectivities
3> Bluetooth / infrared connectivity and data transfer
4> files systems i.e. which type of files can be supported by the mobile operatiing system eg. .doc, .xls, .pdf
5> radios, media players testing.
6> sim-card detection and its connectivity with base station.
I have nothing to declare except my genius. -Oscar Wilde