Can you hear enemy radio?
Not unless they and you are tuned to the same channel and if the channel # is 200 or greater.
how do you voice chat?
Pressing F12 and talking broadcasts your voice on the range channel. Everyone on your country in range will hear you.
Pressing the "t" key and talking broadcasts your voice on whatever channel radio 5 is tuned to. This is used by squads to talk to each other.
is there a way to talk to everyone on your team at once (bishops,knights,rooks)
For voice, only the above two options.
For text typing, there are also various channels. Channel 2 is the general all-country channel (everyone in your country seeing it). Channel 200 by convention is the everyone channel (altough some people don't tune a radio to channel 200 because they don't care to see all of the banter).
ok main thing is so, how many radio station thingys are there, how do I change station, and how do I talk over it?
To talk on a voice radio, see above. To type into a text radio, you hit the key corresponding to the radio. Pressing the "/" key brings up radio 1. "Shift-/" brings up radio 2, and so on (you will see them when you hit "/" key for example). Type some text into the buffer and press "Enter" key. Your text will be broadcast on that radio's channel.
There are four text radios (1-4) and one voice radio (radio 5). You change the channel on a radio by typing, for example, ".radio 5 132" to tune radio 5 to channel 132. Or you can click in the channel indicator of the radio you are interested in and type in the channel.