Hello Terry,
1. Your query as originally asked, looks to be managed with a BDC program.
2. Because your query transformed into another, like your requirement would be to stop the users from creating Orders on technical objects, in case open Order are there on them. This can be easily achieved through user exit IWO10009, through which you can prevent users from creating new orders (stops at SAVE event), if one or more Orders on the Equipment (or F/Locn) are in CRTD or REL state.
3. In either case, it is an ABAP solution. Second one is very simple for your ABAPer.
Good luck
KJogeswaraRao