Almost every system on a ship needs this same sort of design reasearch before it can be mounted on a ship. As a rule of thumb, the only systems that get around this are crew quarters,survey sensors, fuel tanks, engineering, cargo holds, cryogenic holds and cargo handling systems. Basically systems that do not have multiple reasearch lines. If there seem to be more than one reasearch line that affects a particular system then it will need to be designed and reasearched after getting the background tech. As a side note, you will also need to design your missiles in the same way using the missile tab, and for designing turrets, you first have to reasearch the specific weapon design you want in the turret (turret tab). Currently only lasers, mesons, and gauss cannon can be put in turrets. If you want point defence to shoot down incomming missiles you will probably want to design turrets with a good tracking speed. Try to get the turret tracking tech line to match your fire-controll speed tech line if possible.
Brian