kyparamedic said:
Would all of them be hardwired into the system?
Not necessarily, no. Just to run a radio to dispatch from, they wouldn't have to be. There are many dispatching configurations on trunked systems that are nothing more than a subscriber radio set up as a base with a beam antenna pointed at one of the systems' sites, or worse, a mag-mount mobile antenna stuck on top of a refrigerator! For more functionality, yes, they would be hardwired, depending on what they need to do. It is usually done over leased-line, sometimes telephone circuits, sometimes T1 or other data lines.
kyparamedic said:
Would they have to be in order to pre-empt other users, read user ID's, and reset emergency activations?
To preempt, reset, patch, and other extended functions, almost certainly yes. Reading radio IDs is possible right from the control channel, which is why its also possible to do it with Unitrunker and other control channel decoding software out there.