C/V Constant velocity driveline. It takes out the U-joint chatter in turns. Most brands now have the springs in the cylinder to take out some of the bounce.
3 Hydraulic outlets lets you raise the wings seperately and have height adjustment. I only have 2 so my wings are plumbed together.
You can't easily turn off 1 wing. They claim you can run them with 1 wing folded up in the up position, but I never was comfortable seeing the blades spinning like that myself. I keep it all down when mowing road ditches and adjust the heigth to keep it out of the gravel.
In the size your looking at 1000 rpm would probably be standard for your tractors, wouldn't it? I use 540 but that is what all my equipment is set up for. You should be able to do 5 mph over open fields in grass, weeds, or cornstalks pretty easily.
I have owned to 2 Rhino's and I Bush Hog brand over they years. All have been good machines. I don't really care for Woods either.(thats just a personal preference though) Landpride, Shulte and Modern are all supposed to make good machine's also. I think you can even get much larger size in the Shulte according to the ads I've seen.