The first two pictures show how the in tank side is, you can see the plastic screen, but no teeth, its a smooth surface. The nest shot is of the aqualifter pump, it sits right on top of the back of the overflow. This removes the air and water from the ledge so that it can flow freely to the back and then go down the pipes. The aqualifter has an intake side and an output side. The inout gets attached to a nipple on the top of the overflow and the output is an airline tube that runs right into the back section. The last picture is of the dual sponge prefilter. This will catch any large particles so that it doesnt run down the pipes into your sump.
Anything that does get by the first screen and the prefilter sponges will be caught up by the filter sock.
You might want to get a couple filter socks as backup so that you can wash the sock and still have the filter run with one. You'll need square socks, which is a pain but you can also kinda fit the round ones in too. I have about 8 socks, most of them I got from the last group buy, BRS has them for like $5 each.