Yeah, the only reason he is being a bit gentle right now is because he is interacting with them personally. Once it becomes large-scale, he'll drop this attitude.

He completed the quests + defeated several floor bosses!

It does! To be specific it means ghost in Japanese!

Depends on what the system classifies as a weapon. If you check the item details, you'll see that he can only use [Items with ATK stat] as weapons. The same rule doesn't apply to normal humans or other races, only to him.

He's more of a rational type, he wants to kill but is not going to head in without a plan. You'll see that later in the story too. Yk, can't have the MC die again and again by jumping into a holy barrier or something

MC is going to be a slaughterer, but he won't go out of his way to kill non-involved people! Of course, if it suits his goal, then he'll massacre anyone and everyone. But even if he kills others, he will always show respect to the innocent ones, which is why he buried Lily but not Bayek.

Haha, well, he has been pushed around for long so... he needs to be careful!