I think the comment about Home Depot was only meant to convey that you would be wise not to take their advise to heart, and the advice you were given is incorrect.
If you do not have the bond wire in your armored cable you will need 2 gfci's and you can forget the wire the HD guy suggested. If you have that bonding wire then no gfci is required at all. But you should test to make sure your ground is good. The tester shown earlier will do that. Or a voltage tester placed with one probe on the metal box and one on the hot wire or screw of the receptacle will work ... it should show 120 volts or the light should come on.
If no bonding wire in the armored cable you will need one gfci for the switched receptacle and then a gfci installed at the first receptacle after the switched gfci one. Connect the cable wires (black and white) coming from the switched gfci box to the 'line' terminals of this gfci. Then the cable that goes to the other regular grounding type receptacles needs to be connected to the 'load' terminals (screws) of that gfci. In the box with the gfci will be several labels saying "gfci protected no equipment ground" ... place those labels on the faceplates of the non gfci receptacles in the circuit. Be sure your switched gfci has neutral and hot connections to the 'line' terminals only .. the 'load' terminals will be unused on this gfci..
" One nice thing about the NEC articles ... you have lots of choices"