For 1) no, other means can be done. iPhone does it one way (with their zoom loupe), but other means can be used, either on-sceren or off-screen, depending on if there are hardware keys or not. 2) Well, touch screens work well with games suitable for touch screens. Just like you wouldn't enjoy Civilization with only HW keys (well, some do!), you wouldn't probably enjoy Quake with only the touch screen.