There are multiple occasions when drones were hunting russian helicopters. Tough target to kill with one FPV drone.
It is not anywhere near a daily occurence. Beginning of the war or on the rs side, sure, but it's suicide for a rs helo to come into Ukrainian territory at this point.
Yes, but they're generally not right at the front.
It's not trivial to hit them with drones - but there so, so many these days, the density makes things dramatically hard. They are there waiting for movement of supplies.
They had them in the first months of the war but a lot got shot down.