Much is made of the Unsub's strength because they twisted a head round and tied wire.
Except, tying barbed wire has nothing to do with strength. Wire is quite malleable and (if necessary) pliers are widely available, the problem is the barbs and the unsub just wore gloves.
And it's physically impossible to snap a neck or twist a head 180 degrees if the body is not restrained. Since the victim was dangling off the ground, he would have just spun round.
Hotchner says "Jeroboam followed in succession after King David.", but Jeroboam was not part of the succession.
Jeroboam was the first king of Israel, who made a deal with God to gain power in exchange for destroying the line of David and following God's rules. Jeroboam followed his own rules and God cursed him and his bloodline.
Malachi and JJ get on the elevator on floor 2, as indicated by the signs on the door frame. After Malachi and Cissy have their "visit your daddy's grave recently" exchange; Hotch, JJ, and Cissy get off the elevator. The signs on the door frame still say "2."