They reset when you turn the ignition off and back on again, so yes, you will need to reset the switch.
If it stops raining and dries up, then starts raining again, the wipers will come back on automatically provided you have not turned the ignition off.
It's normal, think it says this in the manual iirc.
The annoying thing for me is the rear wiper which smears crap across your back window if you put it in reverse when you're in this mode!