Hi Nomad,
In most Pocket PC's on the market, the video mode is 16-bit truecolor (EDSP_TRUE16). There may be a rare case of 12-bit (EDSP_TRUE12) and future Pocket PC's may support 32-bit (EDSP_TRUE32). We recommend optimizing for 16 and 32 bit (and 12 bit when targetting Symbian devices).
Regarding rotation, the pitch members of E2DSURFACEINFO should be all you need to determine if a direct copy should be used, or a rotated copy.
