what exactly do we need at LB?

i'm guessing quay is still the MLB, is that still a sideline to sideline enforcer type like urlacher? or is it something different? or does he play one of the other two spots like WLB?

are weakside and strongside still a thing like they were when we last ran the 4-3? weakside = playmaker, strongside = thumper

or is that not a thing anymore,

what would the safety/LB hybrid play? is that the MLB?

what kind of player exactly do we need for those 2 spots?