On this item what is the what looks like a 1/4 " tubing on the suction side that goes to the top area

We would encourage you to watch the video on the product page of our website which shows the Dust Deputy in use.The hose shown in the photo goes between the dust cyclone and the dust port on the Festool CT Dust Extractor. The hose supplied with your Dust Extractor would be plugged into the other port on the cyclone. As dust comes through the hose from the tool, the cyclone separates fine dust from the more coarse dust. The coarse dust is collected in the Dust Deputy's bin. The fine dust will continue to your dust extractor's filter bag.