Update - I think I am OK:
1) Went to the dealer and explained to the service department what went on, complete with pics of the offending steps. Tractor still has warranty, so I wanted to be sure I got the right process & documentation before turned any wrenches. They opened a warranty ticket (to document), and JD paid for a hose and 10qts of coolant. They would do the work if I wanted, but it would be 3 - 5 days before they could get there, and said it was OK (i.e. warranty still in place) if I do the work. Advised me to start it, and watch the stuff discussed here, and shut down if anything out of the ordinary happened. Also advised me to keep the hose and my pics for future discussions. If there was a problem, they would come get the tractor. Gotta say, other than the longish lead time for having a mechanic, this is about as good as I could ask for (I know some would say if JD hadn't made the mess, I wouldn't be down at all, so snap to it, but given the scope of the work - hose and coolant took me about an hour, I'm OK with it. Took me longer to get the paperwork started)
2) Got the hose changed out, and took some measures to avoid a future problem - more on that in another post.
3) Filled system with 10 qts of JD 50/50 coolant. Capacity is supposed to be 12 qts, so it lost most of it.
4) Started tractor. Ran it easy for a few minutes watching temp gauge, white smoke, or anything else strange - nada
5) At no load (sitting still) ran the rpm to about 1700 for 20 mins or so looking for signs - nothing
6) Temp gauge went to about 40% - normal. Turned on the heater, and the output got hot.
7) Drove about 1/2 mile on road towing a batwing to get rig to my shop. No problems.
8) Shut it down and worked on cleaning up the hoses for the EA grapple, then checked the oil - no water, same level.
So, I'm calling it good for now. I will change the oil and filter tomorrow (due anyway), and get back in the field.
Thanks all for the advice. I will post a few pics soon.