1. No you can not talk to walkie talkies, only to a hand held CB walkie talkie. Which is different. You will not talk to the standard walkie talkies they are on different frequency bands.
2. It depends on what kind of set up? one inside? or one out in the vehicle? It all depends on antennas. and the set up. The higher the better, the taller the better, but generally anywhere from 4 to ...10 miles...
at a base station anywhere from 4 to .... 15 miles.
Im not talking 15 miles traveled by road, but by air. so its not too bad.
this is using the standard CB. Some come with Sideband, and will allow you to talk at least double the distance. but only to others with side band (yes their are a lot out there)
3. it depends on the set up, in the mobile you can get a cheap radio and a cheap magnet mount antenna and be set with under a hundred bucks, but its a very mediocre set up, you want a radio with a name, galaxy, uniden, cobra, ect. And a good magnet mount antenna, maybe a wilson 1000 or wilson 2000, or anything TALLER
If you go base station, you will need to buy a radio with a bilt in power supply ( a base radio) or a radio and a power supply ... which a power supply, (small 4 amp) will run about 50 bucks, a decent radio 70 or more. and than a $70 Antenna (imax 2000, or Antron 99) And then some coaxal cable)
... i guess that kinda answered 4 as well...