So, the game technically has player killing, but it’s been massively reduced since the early game, as it was pretty unpopular with the users. You can just turn off friendly fire in the options, and that stops it in virtually all situations. There are some locations, like the power plants, that you can take over from enemies and other players can take from you, though it’s rare that I’ve seen that happen. And if you create a locked door in your CAMP and someone lockpicks it, they get a bounty and can be killed.
On PC, I’ve found it to be pretty stable (probably the most stable in the series, by Fallout standards). I’ve seen a few bugs, the most-irritating of which is that sometimes you can’t pick up an item from a corpse and need to look away and then back at the corpse to be able to pick it up.
The loading of assets is considerably less smooth on my system than with the Starfield engine. Starfield can keep a buttery-smooth 165Hz. Fallout 76 will get momentary frame rate reductions. Also, the occasional graphical artifact; haven’t seen that in Starfield.