Can I temporarily use device with physical QWERTY in touch only mode? I am looking for a new phone with a physical QWERTY keyboard (probably a "slide-down" construction). As I do not have possibility to test it, I would like to know, whether I can use the device as a standard touch phone without using the physical keyboard if needed. 

How does Android behave when the physical keyboard is not activated (the slide-down phone is folded)? Do I have to manually activate the virtual one or is it automatic?

thanks
Yes, the phone should behave same as without physical keyboard until you open the physical keyboard which will cause hiding the virtual one.