My first question is; How does the loot respawning work? For officials for example, does it restart the server like once a day and refreshes the loot?: You are correct on that. Most servers restart about every 8 or 12 hours form my experience. I don't go on forums much myself though.
Also, on player owned server, is it set by the admin at which rate the loot refreshes?: Yes.
When loot refreshes, do the doors close as if it was an unlooted building or they remain opened but just the loot refreshes?: I think they close. Most likely.
Does everybody kill you on sight?: Almost. If they laugh and you're a freshie, run. They are a cannibal and will kill you. They will always kill you if you're geared. You have a chance as a freshie. The very few encounters I've had with players since I started yesterday were everything but peaceful. I was walking a road that seemed to lead to a big city, and i'm guessing this guy was leaving it, saluted me and started popping shots. Granted he was absolute garbage i managed to juke him behind a couple trees and run away. Are there any friendly players out there?: Hardly. Expect really geared players to be hostile, but they might be neutral. If you're a freshie. Freshie V Freshie is your best chance at friendly encounters. Chance.
The previous question brings me to this one; do you have a recommendation for a friendly private server?: Sorry, I don't. I'm trying to RP as a Hero/Helper but I can't manage to gear up because every encounter I come by I try to talk with people and they end up killing me.