Neuroscience: zapping an axon connected to thermoreceptor
I and II depend on the type of electrical signal applied to the axon. for III, most receptors can perceive other sense as well, so for example striking a vision receptor may produce the perception of light (even in complete darkness) - my guess is the you would feel pain, even if you could isolate the destructive signal away from nearby pain receptors. 

search "action potential" in duckduckgo.com, it will get you going.