My sincerest apologies for not having the write up finished yet. I have had a few unexpected tasks thrown at me at work, and have been buried... I will get this up as quickly as possible.
I haven't but I have a radioddity truck radio on the way, so I will have an idea of what I think of something from them. Overall internet reaction seems positive to their private labeled radios.
Per this, yes. I haven't programmed mine with Chirp yet.
https://chirp.danplanet.com/projects/chirp/wiki/Home
I have one of these on the way for a repeater build and I can give you my thoughts once I get it (supposed to be delivered 7/15).
These truck radios, with the higher TX power and a good whip (the one I linked comes with a whip antenna) will cover a LOT more distance than a handheld.
With repeaters? Yep. Direct? Likely not. I can hit the BARC repeater at NCAR from the basement of my house in SE Longmont, but that's a very nice set of antennas, filters, and radios (been there when I was in BARC Jr, and got to "help" tune a new filter that was installed).
That's a pretty good rule of thumb, but it is conservative, as evidenced by my ability to hit and use the BARC repeater at NCAR from my house. Google earth says that is 14 miles. This is with my uv-5r+ and either the 8" or 15" Nagoya/Radioddity antennas.
The 2 meter Ham band is better (140MHz) with terrain and obstacles, because it will bend and push through better than the 400MHz of the 70cm Ham band and the FRS band. The FRS/GMRS/70cm band is WAYYY better than the modern 900MHz digital radios used by LE/FD/EMS, unless you have a trunked repeater setup like they do. Handheld to handheld will blow in the 900MHz band.
Basically, the lower the frequency, the better it will perform over distance. Think about FM radio stations (80-100MHz) vs AM radio stations (.5-1.7MHz). AM covers so much more ground, because it has a frequency that is so much lower. AM and FM stations are generally pretty similar in output power.
Make sure your radio output is in line with the expected input of the amp. If you are over/under driving the amp, it won't be happy, and won't play nice.
Yes, and yes. The only caveat to talking to other radios is that some FRS radios can run "security" to make your conversations private, so if others are using that, you can't hear what they are saying, just noise.