None of your concerns are new, they've been floating around for a while.
All good points, but I suspect that many do not understand the purpose of FirstNet.
FirstNet is not intended to replace two way radio systems. Yes, it will carry voice traffic, but even FirstNet will tell you that it's not the intended purpose. It will support PTT voice over cellular, but the product out there are intended to interface to existing two way radio systems. The idea that someone can monitor traffic, talk back if needed, but the "boots on the ground" will likely still be carrying a radio for many years to come.
There is some manufacturers that are playing around with 900MHz simplex stuff. Very short range, similar to the old Nextel DirectConnect. 1 watt 900MHz isn't going to replace "real" radios.
One company at APCO was showing off a P25 "sled" that mounted to the back of a FirstNet handset. The idea was that it would handle the voice traffic into the network. The product had no labels, just something they were playing with in their lab.
FirstNet is intended to be a broadband data service. Your local agencies are already using terminals in their vehicles, often using slow speed data over a radio link, or using one of the existing carriers. FirstNet can replace that and add some benefits. But, many agencies will stick with what they have, Verizon, etc.
Handsets can be a bit pricey, but many are purpose built devices, much more rugged than a consumer smart phone. Some have easily replaceable batteries, louder audio, actual PTT buttons, knobs, etc. Audio interface connectors look more like 2 way radio speaker mic connections, not cheesy 1/8 plugs.
Take a look at some of the Sonim products to see some examples.
Preemption will have multiple levels, actual public safety users will have higher priority, lower tier FirstNet users will have lower priority. Lower tier users might be public works, hospital workers, relief agencies, etc. There's some flexibility in the network to support this.
Some of the better benefits will come when the applications designed for FirstNet are released. FirstNet has a specific "App store" that will provide appropriate public safety applications.
There's no requirement that any agency switch to FirstNet. We're looking at it where I work, but we may just stick with Verizon, as they are offering many of the same features.
Service plans are similar to consumer pricing. Some of it is cheaper. Some states are doing their own contracts, we were seeing things on the order of $40/mo for unlimited voice, data and text.
Don't necessarily go off the prices at FirstNet.com, agencies will/should negotiate something better.
Yeah, there's a lot of hype, and it's good to be skeptical, but give it time.