Surprisingly people on the pirated servers are a lot friendlier/non-aggressive than people on real servers, but there's also a greater incidence of hacking.
It's not really necessary, you can always type in direct chat with people you're around. Downside is you can't say anything if you're being attacked and running, but usually you can find some method to buy you time and type (ie, going indoors, up a slope, on a dock.) anyway it's not critical that you use a mic.
I'd like to play sometime; I'll join the steam group one day soon after I finish a Touhou game to feel more in-group. All the claimed complaints in this thread about DayZ are true, but this game is still the most fun I've had in a video game in a long time.