My LandPride rotary cutter has that bell shaped plastic shroud. I do not have a slip clutch. I assumed it was there for shrapnel control when a shear bolt lets go. It worked poorly, the bolt went right through it. Never did find the nut end on the first one, or the head end on the second. It is in my future to remove it. Makes it a pain to get to the bolt, and what the heck, it ain't serving a useful purpose anyway. It's cracked in 2 places now, and the cutter probably doesn't have 10 hrs on it. I suppose they have it there to keep the weather off the slip clutch, and it is standard equipment, even if the slip clutch isn't.
As far as shipping with/without the shaft connected to the tractor, I would personally be upset if they shipped without making the connection. Depending on how easy the shaft slides, it can fall out if not connected, or just fall far enough that it would catch on the tractor under the axle, etc.. It flops around if not tied down. If I buy a new piece of equipment with a tractor, I'd just assume it would show up connected properly. And if it didn't, I'd want to know why, and have them do it before I accepted delivery. Just my view and $.02.
Nick