1- you could probably do well with just 8, but 304 will give a better chance of getting a channel that no one else is on.
2- VOX is basically voice activation, meaning you don't need to press a key to transmit.
3- Im in the US so prices are different
4- Don't need a headset unless your in a loud location then it may help.
Something to keep in mind the range data that they show isn't as accurate as it seems, they advertise the range of radios assuming a clear path in a straight line, they work line of site so trees, buildings and other obsitcles may interfere with how far you can use them

Also remember that anyone with a basic scanner or HAM radio will be able to intercept your transmission so don't be giving out "personal" info . LOL