This server is set up for hard survival. You can kill other players, even squad mates.
My reasoning behind this is that it is a survival game, and it has such a good simulation on everything else – it wouldn’t make sense if players were invulnerable to bullets.
Stay sharp, and check your angles – and you should be fine.

Your target will be hurt or dead…
Essentially, there are no expressed rules against engaging in PvP actions. I do, however, strongly suggest that you all treat it as a PVE server. Accidents happen. We’ve all experienced friendly fire in similar gameplays.
If the accident spawns a train of vendetta actions, though – or if there’s any sort of intentional and overt killing of players – you may be kicked and banned from the server.

No. You’re allowed to build your base where ever you want, even in towns and cities. For now, at least.
With update 0.85 (or possibly earlier) the option to put a flag inside an excisting structure was taken out.
The flag now has to be built outside permanent buildings.

There has been made 1 change to the lockpicking on this server, and that is player locks are unpickable.
This is a PVE server after all, and this is done to prevent PvP activities. Thinking that players should be able to keep their hard earned stuff without fear of other squads raiding their bases and stealing their possessions.
Any other lock on this server is at standard values.

No. The sentries stay. Make your desicions accordingly.

The days in the game pass 3,8 times faster than our IRL days. Which means a full day in SCUM passes in 6,3 hours.
The day starts at 08:00, with a sunrise starting at 04:00. Sun sets at 23:00. These are in-game hours.
Most players will have a wrist watch that can help tell the exact time. The server-search window also displays the in-game time for your selected server.

Short answer: Yes.

Take care, and remember where you put them. Use focus mode (hold right mouse button) to spot where the mines/traps are.
Grenades will reveal their location soon enough.