"I am not entirely sure that I know what I am looking at. Does the HDD stick out of the docking station?"
Yes.
"Would I then connect the USB cable to my imac?"
Yes.
"Would that be faster than FW800?"
No. FW800 will be considerably faster, but it will cost considerably more.
Other World Computing _does_ have a "SATA docking station" that has USB2, FW400, FW800, and eSATA, but it costs about $80. Check their site for the "Voyager" series.