Unfortunately, this is all so true. But for the OP, if dispatching is carried out from more than one jurisdiction (say FD and PD in this case) in the same dispatch center, yes there can be multiple bands and/or technologies utilized by each individual department. It all depends on the radio consoles, each having to be compatible and programmed to the system in use. OR, with advanced enough console ability and design, be able to switch each console.Completely a political rather than a technical question. Watch your local media, city and county commission meeting minutes. If a change like that is coming, those groups will be discussing it.
Only in places where there are people that know what they are doing that submit accurate information to keep the database current.The RR database is the best place for system information.
Check out your local government web sites. In many places the city council and county commissioners court (or whatever they call the county administration in your state) post meeting agendas, meeting minutes, bid proposals, reports from outside consultants and other interesting stuff about expensive projects on their web sites. You might be surprised what you can find.Media coverage on the new systems going in sometimes very short on information; sometimes it is never covered at all.