
MC can't die unless he completes all of the weird requests from his dead friends???

It's the survivor's guilt. His conscience is preventing him from killing himself because of the guilt. He feels the need to accomplish their will before he can off himself. Their will's doesn't bind him physically. It's just that he can't bear the guilt of letting himself off easy by ending his life when his comrades died through horrible deaths.
I suppose he can't off himself yet since he wants to honor or respect the death of his comrades by completing their wills. It's a mental shackle(  ̄- ̄)

is the omega a weak pathetic little wussy?

No, the opposite he is tall and strong, he just got the hots for this one alpha, but he is the one who protects the alpha and the dominant one in the relationship.
The brother of the ml is even after a bigger monster omega in his story, so it looks like their taste if a bit different from Keith in Kiss me liar. :)
The way he reacted to being rejected... My precious bgg. I would've chosen him any day of the week.