×you just have to try until you succeed; you don't have to hit any orb until you arranged ALL the roaches so they are all IN the trap or at least on the edges.
There is no trick (that I know about, of course) to do this other than try and try and try.

×You have to open the trap rooms in the right sequence.

×Keep an eye on the position of the crumbly walls and try to figure out where the roaches on the edges will go if you open a trap room before another one and you'll see that there is a sequence using wich the roaches on the edges won't move (or at least they will move IN an enclosed area). To figure out the roaches movement keep in mind the hint I gave you about level 9 in general.

×I think it might be easier if you start from se section and go counterclockwise

×This room is all about the order in which you get the roaches where they need to be, and then the order in which you open the doors. There is a connection between the orders.